Polymeric binders incorporating light-detecting elements and related methods

ABSTRACT

In accordance with certain embodiments, semiconductor dies are embedded within polymeric binder to form, e.g., light-emitting dies and/or composite wafers containing multiple light-emitting dies embedded in a single volume of binder.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/085,046, filed Nov. 20, 2013, which is a continuation of U.S. patentapplication Ser. No. 13/768,267, filed Feb. 15, 2013, which is acontinuation of U.S. patent application Ser. No. 13/748,864, filed Jan.24, 2013, which claims the benefit of and priority to U.S. ProvisionalPatent Application No. 61/589,908, filed Jan. 24, 2012, and U.S.Provisional Patent Application No. 61/589,909, filed Jan. 24, 2012, theentire disclosure of each of which is hereby incorporated herein byreference.

FIELD OF THE INVENTION

In various embodiments, the present invention generally relates to lightsources, and more specifically to phosphor-converted light sources.

BACKGROUND

Light sources such as light-emitting diodes (LEDs) are an attractivealternative to incandescent and fluorescent light bulbs in illuminationdevices due to their higher efficiency, smaller form factor, longerlifetime, and enhanced mechanical robustness. However, the high cost ofLED-based lighting systems has limited their widespread utilization,particularly in broad-area general lighting applications.

The high cost of LED-based lighting systems has several contributors.LEDs are typically encased in a package, and multiple packaged LEDs areused in each lighting system to achieve the desired light intensity. Forgeneral illumination, which utilizes white light, such white light maybe generated in a number of ways. One approach is to utilize two or moreLEDs operating at different wavelengths, where the different wavelengthscombine to appear white to the human eye. For example, LEDs emitting inthe red, green and blue wavelength ranges may be utilized together. Suchan arrangement typically requires careful control of the operatingcurrents of each LED, such that the resulting combination of wavelengthsis stable over time and different operating conditions, for exampletemperature. The different LEDs may also be formed of differentmaterials, for example, AlInGaP for red LEDs and AlInGaN for blue andgreen LEDs. These different materials may have different operatingcurrent requirements as well as different temperature dependencies ofthe light output power and wavelength. Furthermore, changes inlight-output power with time may be different for each type of LED.Therefore, such systems typically utilize some form of active control ofthe current in each LED to maintain the light output power of each LEDat the desired level. In some implementations one or more sensors (forexample to sense light intensity, light color, temperature or the like)may be used to provide feedback to the current-control system, while insome other implementations the current may be adjusted over time basedon values in a look-up table. Such control systems add cost andcomplexity to lighting solutions, as well as creating additional failurepoints. A further disadvantage of multi-LED arrangements is that theytypically require some form of light combiner, diffuser or mixingchamber, so that the eye observes white light rather than the discretedifferent colors of each of the different LEDs. Such light-mixingsystems typically add cost and bulk to lighting systems as well asreducing their efficiency.

White light may also be produced in LED-based arrangements for generalillumination by means of light-conversion materials such as phosphors.LEDs generally emit in a relatively narrow wavelength range, for exampleon the order of about 20-100 nm. When broader spectra (for example“white” light) or colors different from that of the LED are desired, theLED may be combined with one or more light-conversion materials. An LEDcombined with one or more phosphors typically generates white light bycombining the short-wavelength emission from the semiconductor LED withlong-wavelength emission from the phosphor(s). This occurs because aportion of the LED light passes unconverted through the phosphor tocombine with the phosphor-converted light. Phosphors are typicallycomposed of phosphorescent particles such as Y₃Al₅O₁₂:Ce³⁺(cerium-activated yttrium-aluminum-garnet, or YAG:Ce) embedded in atransparent binder such as optical epoxy or silicone and applied as alayer. However, phosphor integration is often difficult, particularly interms of uniformity and reproducibility of the resulting light.

In some phosphor implementations, the phosphor layer absorbs a portionof the incident short-wavelength radiant flux and re-emitslong-wavelength radiant flux. In an exemplary YAG:Ce phosphor, asdepicted by the graph in FIG. 1, a blue LED typically has a peakwavelength of 450 nm-460 nm, corresponding to the peak of thephosphor-excitation spectrum, while the phosphor emission has abroadband spectrum with a peak at approximately 560 nm. Combining theblue LED emission with the yellow phosphor emission yields visible whitelight with a specific chromaticity (color) that depends on the ratio ofblue to yellow light. Herein, “white light” may be white or any othercolor that is produced by a combination of light from one or more lightemitters and one or more light-conversion materials.

The geometry of the phosphor relative to the LED generally has a verystrong impact on the uniformity of the light characteristics. Forexample, the LED may emit from more than one surface, for example fromthe top and the sides of the LED, producing non-uniform color if thephosphor composition is not uniform over these LED surfaces. Morecomplicated structures may be used to attempt to mitigate this problem,but these add cost and complexity and may be additional sources forreliability problems.

Furthermore, if the thickness of the phosphor layer, formed of auniformly dispersed phosphor in a binder, is not uniform over thesurface of the LED, relatively larger amounts of blue light will bepresent where the phosphor-infused binder layer is thinner andrelatively smaller amounts of blue light will be present where thephosphor-infused binder is thicker. In view of the foregoing, a needexists for structures, systems and procedures enabling the uniform andlow cost integration of phosphors with LEDs.

SUMMARY

In accordance with certain embodiments, semiconductor dies such aslight-emitting elements (LEEs) are coated with a polymeric binder, whichis subsequently cured to form a composite wafer of the solid bindermaterial and the dies suspended therein. The composite wafer may bedivided into free-standing “white dies” each composed of the die and aportion of the cured binder that at least partially surrounds the die.The binder may advantageously contain a wavelength-conversion materialsuch as a phosphor or a collection of quantum dots. Various moldsubstrates and/or molds may be utilized to secure the semiconductor diesand/or to prevent coating of the contacts of the dies during the coatingprocess.

As utilized herein, the term “light-emitting element” (LEE) refers toany device that emits electromagnetic radiation within a wavelengthregime of interest, for example, visible, infrared or ultravioletregime, when activated, by applying a potential difference across thedevice or passing a current through the device. Examples of LEEs includesolid-state, organic, polymer, phosphor-coated or high-flux LEDs,microLEDs (described below), laser diodes or other similar devices aswould be readily understood. The emitted radiation of a LEE may bevisible, such as red, blue or green, or invisible, such as infrared orultraviolet. A LEE may produce radiation of a spread of wavelengths. ALEE may feature a phosphorescent or fluorescent material for convertinga portion of its emissions from one set of wavelengths to another. A LEEmay include multiple LEEs, each emitting essentially the same ordifferent wavelengths. In some embodiments, a LEE is an LED that mayfeature a reflector over all or a portion of its surface upon whichelectrical contacts are positioned. The reflector may also be formedover all or a portion of the contacts themselves. In some embodiments,the contacts are themselves reflective.

A LEE may be of any size. In some embodiments, a LEEs has one lateraldimension less than 500 μm, while in other embodiments a LEE has onelateral dimension greater than 500 um. Exemplary sizes of a relativelysmall LEE may include about 175 μm by about 250 μm, about 250 μm byabout 400 μm, about 250 μm by about 300 μm, or about 225 μm by about 175μm. Exemplary sizes of a relatively large LEE may include about 1000 μmby about 1000 μm, about 500 μm by about 500 μm, about 250 μm by about600 μm, or about 1500 μm by about 1500 μm. In some embodiments, a LEEincludes or consists essentially of a small LED die, also referred to asa “microLED.” A microLED generally has one lateral dimension less thanabout 300 μm. In some embodiments, the LEE has one lateral dimensionless than about 200 μm or even less than about 100 μm. For example, amicroLED may have a size of about 225 μm by about 175 μm or about 150 μmby about 100 μm or about 150 μm by about 50 μm. In some embodiments, thesurface area of the top surface of a microLED is less than 50,000 μm² orless than 10,000 μm². The size of the LEE is not a limitation of thepresent invention, and in other embodiments the LEE may be relativelylarger, e.g., the LEE may have one lateral dimension on the order of atleast about 1000 μm or at least about 3000 μm.

As used herein, “phosphor” refers to any material that shifts thewavelengths of light irradiating it and/or that is fluorescent and/orphosphorescent. As used herein, a “phosphor” may refer to only thepowder or particles (of one or more different types) or to the powder orparticles with the binder, and in some circumstances may refer toregion(s) containing only the binder (for example, in a remote-phosphorconfiguration in which the phosphor is spaced away from the LEE). Theterms “wavelength-conversion material” and “light-conversion material”are utilized interchangeably with “phosphor” herein. Thelight-conversion material is incorporated to shift one or morewavelengths of at least a portion of the light emitted by LEEs to other(i.e., different) desired wavelengths (which are then emitted from thelarger device alone or color-mixed with another portion of the originallight emitted by the LEE). A light-conversion material may include orconsist essentially of phosphor powders, quantum dots or the like withina transparent binder. Phosphors are typically available in the form ofpowders or particles, and in such case may be mixed in binders. Anexemplary binder is silicone, i.e., polyorganosiloxane, which is mostcommonly polydimethylsiloxane (PDMS). Phosphors vary in composition, andmay include lutetium aluminum garnet (LuAG or GAL), yttrium aluminumgarnet (YAG) or other phosphors known in the art. GAL, LuAG, YAG andother materials may be doped with various materials including forexample Ce, Eu, etc. The specific components and/or formulation of thephosphor and/or matrix material are not limitations of the presentinvention.

The binder may also be referred to as an encapsulant or a matrixmaterial. In one embodiment, the binder includes or consists essentiallyof a transparent material, for example silicone-based materials orepoxy, having an index of refraction greater than 1.35. In oneembodiment the binder and/or phosphor includes or consists essentiallyof other materials, for example fumed silica or alumina, to achieveother properties, for example to scatter light, or to reduce settling ofthe powder in the binder. An example of the binder material includesmaterials from the ASP series of silicone phenyls manufactured by ShinEtsu, or the Sylgard series manufactured by Dow Corning.

Herein, two components such as light-emitting elements and/or opticalelements being “aligned” or “associated” with each other may refer tosuch components being mechanically and/or optically aligned. By“mechanically aligned” is meant coaxial or situated along a parallelaxis. By “optically aligned” is meant that at least some light (or otherelectromagnetic signal) emitted by or passing through one componentpasses through and/or is emitted by the other.

In an aspect, embodiments of the invention feature a method of forming acomposite wafer comprising a plurality of discrete semiconductor diessuspended in a cured binder. The plurality of discrete semiconductordies is disposed on a mold substrate, and each semiconductor die has atleast two spaced-apart contacts adjacent the mold substrate. Thesemiconductor dies are coated with a binder, and the binder is cured toform the composite wafer. The contacts of each semiconductor die remainat least partially uncoated by the binder.

Embodiments of the invention may include one or more of the following inany of a variety of combinations. The composite wafer may be separatedinto a plurality of discrete portions each including or consistingessentially of at least one semiconductor die coated with cured binder.After separation the volume of binder surrounding each semiconductor diemay be substantially equal. After separation the thickness of binderadjacent each semiconductor die may be in the range of about 10 μm toabout 5000 μm. Separating the composite wafer may include or consistessentially of laser cutting, knife cutting, rotary knife cutting,shearing, waterjet cutting, abrasive waterjet cutting, die cutting,and/or sawing. Each discrete portion of the composite wafer may containonly one semiconductor die. Each discrete portion of the composite wafermay be a rectangular solid having approximately 90° corners betweenadjacent faces thereof. After formation of the composite wafer, at leastsome of the semiconductor dies may be electrically tested, and theseparated portions may be binned based on the electrical testing. Thecontacts of the at least one semiconductor die in one of the discreteportions may be electrically coupled to spaced-apart conductive traceson a substrate. For example, the contacts may be adhered to theconductive traces with a conductive adhesive, wire bonding, and/orsoldering. The conductive adhesive may include or consist essentially ofa substantially isotropic conductive adhesive electrically connecting afirst contact only to a first trace and a second contact only to asecond trace, and a non-conductive adhesive material may be provided ina gap between the conductive traces.

The conductive adhesive may include or consist essentially of ananisotropic conductive adhesive (ACA) electrically connecting a firstcontact only to a first trace and a second contact only to a secondtrace. A portion of the ACA may be disposed in a gap between the firstand second contacts and may substantially isolate the first contact fromthe second contact. The conductive traces may include or consistessentially of silver, gold, aluminum, chromium, copper, and/or carbon.The substrate may include or consist essentially of polyethylenenaphthalate, polyethylene terephthalate, polycarbonate,polyethersulfone, polyester, polyimide, polyethylene, and/or paper. Theat least one semiconductor die may include or consist essentially of alight-emitting element. The reflectivity or the transmissivity of thesubstrate for a wavelength emitted by the light-emitting element and/orthe cured phosphor may be greater than 80%. The at least onesemiconductor die may be electrically connected to circuitry forpowering the at least one semiconductor die. After separating thecomposite wafer, additional material may be removed from each of thediscrete portions, whereby each portion has a desired shape thereafter.The desired shapes may all be substantially the same.

The composite wafer may be separated from the mold substrate. A secondsubstrate may be disposed in contact with the plurality of semiconductordies coated with binder, and the mold substrate may be removed from theplurality of semiconductor dies coated with binder, the plurality ofsemiconductor dies coated with binder remaining attached to the secondsubstrate. The composite wafer may be separated from the secondsubstrate. Before curing the binder, the contacts of the plurality ofsemiconductor dies may be at least partially embedded within the moldsubstrate, e.g., by at least 2 μm. After curing the binder, at least aportion of each of the contacts of the plurality of semiconductor diesmay protrude from the cured binder. After curing the binder, at least aportion of each semiconductor die proximate the contacts thereof mayprotrude from the cured binder. After curing the binder, at least onecontact of at least one semiconductor die may not protrude from thecured binder. The contacts of each semiconductor die remainsubstantially entirely uncoated by binder. The binder may include orconsist essentially of silicone and/or epoxy.

Coating the plurality of semiconductor dies with the binder may includeor consist essentially of dispensing the binder into a mold anddisposing the mold substrate over the mold, whereby the plurality ofsemiconductor dies are suspended within the binder. Curing the bindermay include or consist essentially of at least partially curing thebinder and, thereafter, removing the mold substrate from the mold. Thesurface of the mold opposite the mold substrate may have a texture(e.g., one configured to enhance light extraction from the curedbinder), and at least a portion of the cured binder have have thetexture after the mold substrate is removed from the mold. A texture forenhancing light extraction from the cured binder may be applied to atleast a portion of a surface of the binder opposite the mold substrateafter removing the mold substrate from the mold. The mold may include orconsist essentially of a plurality of discrete compartments in which thebinder is disposed, and one or more semiconductor dies may be suspendedwithin or above each compartment prior to curing the binder. Eachcompartment may impart a complementary shape to a portion of the binder,the complementary shapes being substantially identical to each other.The mold substrate may define one or more openings therethrough. Atleast a portion of the binder may be dispensed into the mold through atleast one said opening. A portion of the binder may flow through atleast one said opening when the mold substrate is disposed over themold.

Coating the plurality of semiconductor dies with the binder may includeor consist essentially of dispensing the binder over the mold substrate,the binder being contained over the mold substrate by one or morebarriers extending above a surface of the mold substrate. A texture forenhancing light extraction from the cured binder may be applied to atleast a portion of a surface of the binder opposite the mold substrate,whereby the cured binder retains the texture. Curing the binder mayinclude or consist essentially of at least partially curing the binderand, thereafter, removing the mold substrate from the plurality ofsemiconductor dies. A mold cover may be disposed over and in contactwith at least a portion of the binder. The mold cover may include orconsist essentially of a plurality of discrete compartments, and one ormore semiconductor dies may be suspended within or beneath eachcompartment prior to curing the binder. Each compartment may impart acomplementary shape to a portion of the binder, the complementary shapesbeing substantially identical to each other. The binder may contain awavelength-conversion material, e.g., a phosphor and/or quantum dots.Each semiconductor die may include or consist essentially of alight-emitting semiconductor die (e.g., a bare-die light-emittingdiode). The binder may be transparent to a wavelength of light emittedby the light-emitting semiconductor dies. The light-emittingsemiconductor dies may each include or consist essentially of asemiconductor material including or consisting essentially of GaAs,AlAs, InAs, GaP, AlP, InP, ZnO, CdSe, CdTe, ZnTe, GaN, AN, InN, silicon,and/or an alloy or mixture thereof. The binder may contain awavelength-conversion material for absorption of at least a portion oflight emitted from the light-emitting semiconductor dies and emission ofconverted light having a different wavelength, converted light andunconverted light emitted by the light-emitting semiconductor diescombining to form substantially white light. The substantially whitelight may have a correlated color temperature in the range of 2000 K to10,000 K. The substantially white light may hvae a color temperaturevariation less than four, or even less than two, MacAdam ellipses acrossthe composite wafer.

The composite wafer may have a first surface and a second surfaceopposite the first surface, and the first and second surface may besubstantially flat and parallel. The composite wafer may have asubstantially uniform thickness with a thickness variation less than15%, less than 10%, or even less than 5%. The composite wafer may have asubstantially uniform thickness between 5 μm and 4000 μm. A dimension ofthe composite wafer perpendicular to the thickness may be between 5 mmand 1000 mm. The spacing between neighboring semiconductor dies may besubstantially constant across the composite wafer. The spacing may be inthe range of about 25 μm to about 10,000 μm. The thickness of the binderabove each of the semiconductor dies may be substantially the same. Thethickness of the binder above each of the semiconductor dies may be inthe range of about 25 μm to about 4000 μm. The thickness of the binderabove each of the semiconductor dies may be the same to within 5%. Theplurality of semiconductor dies may include or consist essentially of atleast 100, at least 1000, or even at least 4000 semiconductor dies. Thesemiconductor dies may be arranged in an array having substantiallyequal distances between semiconductor dies in at least a firstdirection. The array may have substantially equal distances betweensemiconductor dies in at least a second direction different from thefirst direction. The semiconductor dies may be arranged in a regularperiodic array. a release material (e.g., a mold-release film) may bedisposed over at least a portion of the binder. The mold release filmmay be textured with a texture for enhancing light extraction from thecured binder. The mold substrate may include or consist essentially ofglass, metal, silicone, fiberglass, ceramic, water-soluble tape,thermal-release tape, UV-release tape, polyethylene terephthalate,polyethylene naphthalate, plastic film, tape, adhesive, acrylic,polycarbonate, a polymer, and/or polytetrafluoroethylene. Curing thebinder may include or consist essentially of exposure to heat, air,moisture, superatmospheric pressure, and/or ultraviolet radiation.Disposing the plurality of discrete semiconductor dies on the moldsubstrate may include or consist essentially of application of (i) anadhesive force, (ii) a magnetic force, and/or (iii) vacuum. Prior todisposing the plurality of discrete semiconductor dies on the moldsubstrate, a group of semiconductor dies may be tested to identifysemiconductor dies having substantially equal characteristics, and theplurality of semiconductor dies may be selected from the identifiedsemiconductor dies.

Prior to coating the plurality of semiconductor dies with the binder, astencil defining openings corresponding to positions of thesemiconductor dies may be disposed over the mold substrate. The stencilmay have a thickness in the range of about 0.5 μm to about 25 μm. Thestencil may include or consist essentially of a flexible foil and/or athin plate. The plurality of semiconductor dies may be disposed withinindentations in the mold substrate. The indentations may have a depth inthe range of about 0.5 μm to about 25 μm. The mold substrate may includeor consist essentially of a vacuum chuck and/or an electrostatic chuck,and the positions of the semiconductor dies may be maintained at leastin part by vacuum or electrostatic force. After the composite wafer isformed, the vacuum or electrostatic force may be removed, and,thereafter, the composite wafer may be removed from the mold substrate.Coating the plurality of semiconductor dies with the binder may includeor consist essentially of controlling the amount of binder dispensedover the semiconductor dies in response to a feedback signal. Thecomposite wafer may be removed from the mold substrate by exposure toheat and/or ultraviolet radiation. The binder may contain fumed silica,fumed alumina, and/or TiO₂. The binder may contain at least one additivefor controlling particle settling and/or controlling binder viscosity.The binder may comprise a plurality of discrete regions, at least one ofwhich includes or consists essentially of the binder and at least onewavelength-conversion material. At least one of the regions may consistessentially of only the binder. At least one semiconductor die mayinclude or consist essentially of one or more active layers over asubstrate, and the substrate may be partially or completely removedbefore coating with the binder. The substrate of the at least onesemiconductor die may be partially or completely removed after disposingthe at least one semiconductor die on the mold substrate. Each of thesemiconductor dies may include or consist essentially of alight-detecting semiconductor die (e.g., a die in which charge is formedin response to incipient light such as a photovoltaic die). The bindermay be transparent to a wavelength of light detected by (i.e., resultingin charge formation in) the light-detecting semiconductor dies. Thelight-detecting semiconductor dies may include or consist essentially ofa semiconductor material including or consisting essentially of GaAs,AlAs, InAs, GaP, AlP, InP, ZnO, CdSe, CdTe, ZnTe, GaN, AN, InN, silicon,and/or an alloy or mixture thereof. The binder may contain awavelength-conversion material for absorption of at least a portion oflight incident thereon and emission of converted light (i) having adifferent wavelength and (ii) for detection by the light-detectingsemiconductor die.

An optical element may be associated with (e.g., aligned to) one or moreof the semiconductor dies. An array of optical elements may be disposedon the binder prior to curing. Curing the binder may adhere the array ofoptical elements to the cured binder. The composite wafer may includethe array of optical elements, and the composite wafer may be separatedinto discrete portions each including at least one optical element. Theplurality of semiconductor dies may include a light-emittingsemiconductor die and/or a light-detecting semiconductor die. Areflecting layer (e.g., a reflecting film) may be formed over or withinat least a portion of the composite wafer (e.g., over or within thebinder). The reflecting film may include or consist essentially ofaluminum, copper, gold, silver, and/or titanium. The reflecting layermay include or consist essentially of a plurality of particles (e.g.,fumed silica particles, fumed alumina particles, and/or TiO₂ particles).Forming the reflecting layer may include or consist essentially ofdisposing the plurality of particles over the mold substrate andplurality of semiconductor dies before coating the plurality ofsemiconductor dies with the binder. Prior to coating the plurality ofsemiconductor dies with the binder, a reflecting film defining openingscorresponding to positions of the semiconductor dies may be disposedover the mold substrate. The semiconductor die may include or consistessentially of a light-emitting or a light-detecting semiconductor die,and a reflecting layer may be formed over at least a portion of thesurface of the composite wafer, the reflecting layer having areflectivity of at least 25% to a wavelength of light emitted orabsorbed by (i) the semiconductor die and/or (ii) the binder.

In another aspect, embodiments of the invention feature a method offorming a composite wafer comprising a plurality of discretesemiconductor dies suspended in a cured binder. The plurality ofdiscrete semiconductor dies are disposed on a mold substrate, and eachsemiconductor die has at least two spaced-apart contacts opposite themold substrate. The plurality of semiconductor dies are coated with afirst binder, the contacts of each semiconductor die remaining at leastpartially uncoated. The first binder is at least partially cured. Asecond substrate is disposed in contact with the plurality ofsemiconductor dies coated with at least partially cured first binder.Thereafter, the mold substrate is removed from the plurality ofsemiconductor dies, thereby exposing a portion of each semiconductor dieuncoated by the first binder, the plurality of semiconductor diesremaining attached to the second substrate. At least the uncoatedportion of each of the plurality of semiconductor dies is coated with asecond binder, and the contacts of each semiconductor die remain atleast partially uncoated. The second binder is cured to form thecomposite wafer.

Embodiments of the invention may include one or more of the following inany of a variety of combinations. The first binder and the second bindermay include or consist essentially of the same material. The compositewafer may be separated into a plurality of discrete portions eachincluding at least one semiconductor die coated with cured first binderand cured second binder. The composite wafer may be separated from thesecond substrate. At least a portion of each of the contacts of theplurality of semiconductor dies of the composite wafer may protrude fromcured first binder and/or cured second binder. At least a portion ofeach semiconductor die proximate the contacts thereof may protrude fromcured first binder and/or cured second binder. The first binder and/orthe second binder may include or consist essentially of silicone and/orepoxy. Coating at least the uncoated portion of each of the plurality ofsemiconductor dies with the second binder may include or consistessentially of dispensing the second binder into a mold and disposingthe mold substrate over the mold, whereby the plurality of semiconductordies are disposed in contact with the second binder. Curing the secondbinder may include or consist essentially of at least partially curingthe second binder and, thereafter, removing the mold substrate from themold. A surface of the mold opposite the mold substrate may hvae atexture (e.g., a texture configured to enhance light extraction from thecured second binder), and at least a portion of the cured second bindermay have the texture after the mold substrate is removed from the mold.A texture for enhancing light extraction from the cured second bindermay be applied to at least a portion of a surface of the second binderopposite the mold substrate after removing the mold substrate from themold. The mold may include or consist essentially of a plurality ofdiscrete compartments in which the second binder is disposed, and (ii)one or more semiconductor dies may be suspended within or above eachcompartment prior to curing the second binder. Each compartment mayimpart a complementary shape to a portion of the second binder, thecomplementary shapes being substantially identical to each other.

Coating at least the uncoated portion of each of the plurality ofsemiconductor dies with the second binder may include or consistessentially of dispensing the second binder over the mold substrate, andthe second binder may be contained over the mold substrate by one ormore barriers extending above a surface of the mold substrate. A texturefor enhancing light extraction from the cured second binder may beapplied to at least a portion of a surface of the second binder oppositethe mold substrate, whereby the cured second binder retains the texture.Curing the second binder may include or consist essentially of at leastpartially curing the second binder and, thereafter, removing the moldsubstrate from the plurality of semiconductor dies. A mold cover may bedisposed over and in contact with at least a portion of the secondbinder. The mold cover may include or consist essentially of a pluralityof discrete compartments, and one or more semiconductor dies may besuspended within or beneath each compartment prior to curing the secondbinder. Each compartment may impart a complementary shape to a portionof the second binder, the complementary shapes being substantiallyidentical to each other. The first binder and/or the second binder maycontain a wavelength-conversion material (e.g., a phosphor and/orquantum dots). Each semiconductor die may include or consist essentiallyof a light-emitting semiconductor die (e.g., a bare-die light-emittingdiode). The first binder and/or the second binder may be transparent toa wavelength of light emitted by the light-emitting semiconductor dies.Each light-emitting semiconductor die may include or consist essentiallyof a semiconductor material including or consisting essentially of GaAs,AlAs, InAs, GaP, AlP, InP, ZnO, CdSe, CdTe, ZnTe, GaN, AN, InN, silicon,and/or an alloy or mixture thereof. The first binder and/or the secondbinder may contain a wavelength-conversion material for absorption of atleast a portion of light emitted from the light-emitting semiconductordies and emission of converted light having a different wavelength,converted light and unconverted light emitted by the light-emittingsemiconductor dies combining to form substantially white light. Thesubstantially white light may have a correlated color temperature in therange of 2000 K to 10,000 K. The substantially white light may have acolor temperature variation less than four, or even less than two,MacAdam ellipses across the composite wafer.

In yet another aspect, embodiments of the invention feature a method offorming electronic devices. A plurality of discrete semiconductor diesis disposed on a mold substrate, each semiconductor die having at leasttwo spaced-apart contacts adjacent the mold substrate. The plurality ofsemiconductor dies is coated with a binder. The binder is cured to forma composite wafer including or consisting essentially of the pluralityof semiconductor dies suspended in the cured binder, the contacts ofeach semiconductor die remaining at least partially uncoated withbinder. The composite wafer is separated into a plurality of discreteportions each including or consisting essentially of at least onesemiconductor die suspended in cured binder. Thereafter, the discreteportions of the composite wafer are removed from the mold substrate.

Embodiments of the invention may include one or more of the following inany of a variety of combinations. The binder may include or consistessentially of (i) silicone and/or epoxy and (ii) awavelength-conversion material, and each of the semiconductor dies mayinclude or consist essentially of a light-emitting diode. Thewavelength-conversion material may absorb at least a portion of lightemitted from a light-emitting semiconductor die and emit converted lighthaving a different wavelength, converted light and unconverted lightemitted by the light-emitting semiconductor die combining to formsubstantially white light. After curing the binder, at least a portionof each of the contacts of the plurality of semiconductor dies mayprotrude from the cured binder. After curing the binder, at least aportion of each semiconductor die proximate the contacts thereof mayprotrude from the cured binder.

In an additional aspect, embodiments of the invention feature a methodof forming electronic devices. A plurality of discrete semiconductordies is disposed on a mold substrate, each semiconductor die having atleast two spaced-apart contacts opposite the mold substrate. Theplurality of semiconductor dies is coated with a first binder, thecontacts of each semiconductor die remaining at least partiallyuncoated. The first binder is at least partially cured. A secondsubstrate is disposed in contact with the plurality of semiconductordies coated with at least partially cured first binder. Thereafter, themold substrate is removed from the plurality of semiconductor dies,thereby exposing a portion of each semiconductor die uncoated by thefirst binder, the plurality of semiconductor dies remaining attached tothe second substrate. At least the uncoated portion of each of theplurality of semiconductor dies is coated with a second binder. Thesecond binder is cured to form a composite wafer including or consistingessentially of the plurality of semiconductor dies and cured first andsecond binders. The composite wafer is separated into a plurality ofdiscrete portions each including or consisting essentially of at leastone semiconductor die and cured first and second binders. Thereafter,the discrete portions of the composite wafer are removed from the moldsubstrate.

Embodiments of the invention may include one or more of the following inany of a variety of combinations. The first binder and the second bindermay include or consist essentially of the same material. The firstbinder and/or the second may include or consist essentially of (i)silicone and/or epoxy and (ii) a wavelength-conversion material, andeach of the semiconductor dies may include or consist essentially of alight-emitting diode. The wavelength-conversion material may absorb atleast a portion of light emitted from a light-emitting semiconductor dieand emit converted light having a different wavelength, converted lightand unconverted light emitted by the light-emitting semiconductor diecombining to form substantially white light. After curing the secondbinder, at least a portion of each of the contacts of the plurality ofsemiconductor dies may protrude from the cured first binder and/or thecured second binder (i.e., from the composite wafer). After curing thesecond binder, at least a portion of each semiconductor die proximatethe contacts thereof may protrude from the cured first binder and/or thecured second binder.

In yet an additional aspect, embodiments of the invention feature amethod of forming a composite wafer including or consisting essentiallyof a plurality of discrete semiconductor dies suspended in a curedbinder. The plurality of discrete semiconductor dies is disposed on amold substrate, each semiconductor die having at least two spaced-apartcontacts. The plurality of semiconductor dies is coated with a binder.The binder is cured to form the composite wafer. At least a portion ofthe binder proximate the at least two contacts is removed to expose atleast portions of each of the at least two contacts. The composite wafermay be separated into a plurality of discrete portions each including orconsisting essentially of at least one semiconductor die suspended incured binder. Thereafter, the discrete portions of the composite wafermay be removed from the mold substrate.

In an aspect, embodiments of the invention feature an electronic deviceincluding or consisting essentially of a solid shaped volume of apolymeric binder and, suspended within the binder, a semiconductor diehaving a first face, a second face opposite the first face, at least onesidewall spanning the first and second faces. At least two spaced-apartcontacts are disposed on the first face of the semiconductor die. Thecontacts each have a free terminal end (i) not covered by the binder and(ii) available for electrical connection.

Embodiments of the invention may include one or more of the following inany of a variety of combinations. At least portions of the contacts mayprotrude from the binder. At least a portion of each said sidewall mayprotrude from the binder. The binder may define a rectangular solidhaving approximately 90° corners between adjacent faces thereof. Thebinder may include or consist essentially of silicone and/or epoxy. Oneor more additional semiconductor dies may be suspended within thebinder. The binder may contain a wavelength-conversion material (e.g., aphosphor and/or quantum dots) therein. The semiconductor die may includeor consist essentially of a light-emitting element (e.g., a bare-dielight-emitting diode). The binder may be transparent to a wavelength oflight emitted by the light-emitting element. The light-emitting elementmay include or consist essentially of a semiconductor material includingor consisting essentially of GaAs, AlAs, InAs, GaP, AlP, InP, ZnO, CdSe,CdTe, ZnTe, GaN, AN, InN, silicon, and/or an alloy or mixture thereof.The binder may contain a wavelength-conversion material for absorptionof at least a portion of light emitted from the light-emitting elementand emission of converted light having a different wavelength, convertedlight and unconverted light emitted by the light-emitting elementcombining to form substantially white light. The substantially whitelight may have a correlated color temperature in the range of 2000 K to10,000 K. The binder may have a thickness between 5 μm and 4000 μm. Adimension of the binder perpendicular to the thickness may be between 25μm and 50 mm. At least a portion of the surface of the binder may have atexture for enhancing extraction of light from the binder.

The semiconductor die may include or consist essentially of alight-detecting element. The binder may be transparent to a wavelengthof light detected by the light-detecting element. An optical element maybe positioned to receive light from or transmit light to thesemiconductor die. A reflecting layer may be disposed over or within atleast a portion of the binder. The reflecting layer may include orconsist essentially of (i) a reflecting film and/or (ii) a plurality ofparticles. The semiconductor die may include or consist essentially of alight-emitting element or a light-detecting element, and the reflectinglayer may have a reflectivity of at least 25% to a wavelength of light(i) emitted or detected by the semiconductor die or (ii) emitted by thebinder. The binder may include or consist essentially of a plurality ofdiscrete regions, at least one of which includes or consists essentiallyof the binder and at least one wavelength-conversion material. Anotherof the regions may consist essentially of only the binder. Thesemiconductor die may include or consist essentially of one or moreactive semiconductor layers not disposed on a semiconductor substrate.One or more alignment marks may be disposed on the surface of the binderfor alignment and/or orientation of the semiconductor die.

In another aspect, embodiments of the invention feature a compositewafer including or consisting essentially of a solid volume of apolymeric binder having a first surface and a second surface oppositethe first surface and, suspended within the binder, a plurality ofsemiconductor dies each having a first face, a second face opposite thefirst face, and at least one sidewall spanning the first and secondfaces. At least two spaced-apart contacts are disposed on the first faceof each semiconductor die. The contacts each have a free terminal end(i) not covered by the binder and (ii) available for electricalconnection.

Embodiments of the invention may include one or more of the following inany of a variety of combinations. At least portions of the contacts ofthe semiconductor dies may protrude from the binder. At least a portionof each said sidewall of each of the semiconductor dies may protrudefrom the first surface of the binder. The binder may include or consistessentially of silicone and/or epoxy. The binder may contain awavelength-conversion material (e.g., a phosphor and/or quantum dots)therein. Each semiconductor die may include or consist essentially of alight-emitting element (e.g., a bare-die light-emitting diode). Thebinder may be transparent to a wavelength of light emitted by thesemiconductor dies. Each semiconductor die may include or consistessentially of a semiconductor material that includes or consistsessentiall of GaAs, AlAs, InAs, GaP, AlP, InP, ZnO, CdSe, CdTe, ZnTe,GaN, AN, InN, silicon, and/or an alloy or mixture thereof. The bindermay contain a wavelength-conversion material for absorption of at leasta portion of light emitted from the light-emitting elements and emissionof converted light having a different wavelength, converted light andunconverted light emitted by the light-emitting elements combining toform substantially white light. The substantially white light may have acorrelated color temperature in the range of 2000 K to 10,000 K. Thesubstantially white light may have a variation in color temperature ofless than four, or even less than two, MacAdam ellipses across thecomposite wafer. The first and second surfaces of the binder may besubstantially flat and parallel. The binder may have a substantiallyuniform thickness with a thickness variation less than 10%, or even lessthan 5%. The binder may have a thickness between 15 μm and 4000 μm. Adimension of the binder perpendicular to the thickness (e.g., a sidelength or a diameter) may be between 100 μm and 1000 mm. The spacingbetween each pair of the plurality of semiconductor dies may besubstantially the same. The spacing between each pair of the pluralityof semiconductor dies may be in the range of about 25 μm to about 10,000μm. The thickness of the binder above each of the plurality ofsemiconductor dies may be substantially the same. The thickness of thebinder above each of the plurality of semiconductor dies may be the sameto within 5%.

The plurality of semiconductor dies may include or consist essentiallyof at least 500 semiconductor dies, or even at least 2000 semiconductordies. The semiconductor dies may be arranged in an array havingsubstantially equal distances between semiconductor dies in at least afirst direction. The array of semiconductor dies may have substantiallyequal distances between semiconductor dies in a second directiondifferent from the first direction. The semiconductor dies may bearranged in a regular periodic (e.g., two-dimensional) array. At least aportion of the surface of the binder may be textured with a texture forenhancing light extraction from the binder. Each semiconductor die mayinclude or consist essentially of a light-detecting element (e.g., aphotovoltaic die). The binder may be transparent to a wavelength oflight detected by the semiconductor dies. At least one optical elementmay be positioned to receive light from or transmit light to at leastone of the semiconductor dies. The at least one optical element mayinclude or consist essentially of a plurality of discrete opticalelements each associated with at least one semiconductor die. Areflecting layer (e.g., a reflecting film and/or a plurality ofparticles) may be disposed over or within at least a portion of thebinder. Each semiconductor die may include or consist essentially of alight-emitting element or a light-detecting element, and the reflectinglayer may have a reflectivity of at least 25% to a wavelength of light(i) emitted or detected by the semiconductor dies or (ii) emitted by thebinder. The binder may include or consist essentially of a plurality ofdiscrete regions, at least one of which comprises the binder and atleast one wavelength-conversion material. At least one other region mayconsist essentially of the binder. Each semiconductor die may include orconsist essentially of one or more active semiconductor layers notdisposed on a semiconductor substrate. One or more alignment marks maybe disposed on the first surface or the second surface of the binder.The binder may include or consist essentially of a plurality of shapedregions, each shaped region (i) associated with at least onesemiconductor die and (ii) having a shape substantially identical toshapes of the other shaped regions.

In yet another aspect, embodiments of the invention feature anelectronic device including or consisting essentially of (i) a substratehaving first and second conductive traces thereon, the first and secondconductive traces being separated on the substrate by a gaptherebetween, (ii) disposed over the gap, a semiconductor die having afirst face, a second face opposite the first face, at least one sidewallspanning the first and second faces, and two spaced-apart contacts onthe first face, the contacts each being electrically coupled to adifferent conductive trace, and (iii) encasing the second face and atleast a portion of each said sidewall of the semiconductor die, a solidpolymeric binder defining a rectangular solid having approximately 90°corners between adjacent faces thereof. At least a portion of each ofthe contacts is not covered by the binder.

Embodiments of the invention may include one or more of the following inany of a variety of combinations. At least a portion of each of thecontacts may protrude from the binder. At least a portion of each saidsidewall may protrude from the binder. The binder may include or consistessentially of silicone and/or epoxy. The binder may contain awavelength-conversion material (e.g., a phosphor and/or quantum dots)therein. The top surface of the binder opposite the substrate may have atexture for promoting light extraction from the top surface. Thesemiconductor die may include or consist essentially of a light-emittingelement (e.g., a bare-die light-emitting diode). The binder may betransparent to a wavelength of light emitted by the semiconductor die.The semiconductor die may include or consist essentially of asemiconductor material including or consisting essentially of GaAs,AlAs, InAs, GaP, AlP, InP, ZnO, CdSe, CdTe, ZnTe, GaN, AN, InN, silicon,and/or an alloy or mixture thereof. The binder may contain awavelength-conversion material for absorption of at least a portion oflight emitted from the semiconductor die and emission of converted lighthaving a different wavelength, converted light and unconverted lightemitted by the semiconductor die combining to form substantially whitelight. The substantially white light may have a correlated colortemperature in the range of 2000 K to 10,000 K.

The semiconductor die may include or consist essentially of alight-detecting element. The binder may be transparent to a wavelengthof light detected by the semiconductor die. An optical element may beassociated with (e.g., aligned to) the semiconductor die. A reflectinglayer may be disposed over or within at least a portion of the binder.The binder may include or consist essentially of a plurality of discreteregions, at least one of which includes or consists essentially of thebinder and at least one wavelength-conversion material. Another regionmay consist essentially of the binder. The semiconductor die may includeor consist essentially of one or more active semiconductor layers notdisposed on a semiconductor substrate (i.e., no semiconductor substrateis present within the die). The contacts may be electrically coupled tothe conductive traces with a conductive adhesive. The conductiveadhesive may include or consist essentially of a substantially isotropicconductive adhesive electrically connecting a first contact only to thefirst trace and a second contact only to the second trace, and anon-conductive adhesive material may be disposed in the gap. Theconductive adhesive comprises an anisotropic conductive adhesive (ACA)electrically connecting a first contact only to the first trace and asecond contact only to the second trace. A portion of the ACA may bedisposed in the gap and may substantially isolate the first contact fromthe second contact. The contacts may be electrically coupled to theconductive traces by wire bonds and/or solder. The conductive traces mayinclude or consist essentially of silver, gold, aluminum, chromium,copper, and/or carbon. The substrate may include or consist essentiallyof polyethylene naphthalate, polyethylene terephthalate, polycarbonate,polyethersulfone, polyester, polyimide, polyethylene, and/or paper. Thesemiconductor die may include or consist essentially of a light-emittingelement. The reflectivity of the substrate for a wavelength emitted byat least one of the light-emitting element or the binder may be greaterthan 80%. The transmissivity of the substrate for a wavelength emittedby at least one of the light-emitting element or the binder may begreater than 80%. Circuitry for powering the semiconductor die may beelectrically connected to the semiconductor die.

These and other objects, along with advantages and features of theinvention, will become more apparent through reference to the followingdescription, the accompanying drawings, and the claims. Furthermore, itis to be understood that the features of the various embodimentsdescribed herein are not mutually exclusive and can exist in variouscombinations and permutations. Reference throughout this specificationto “one example,” “an example,” “one embodiment,” or “an embodiment”means that a particular feature, structure, or characteristic describedin connection with the example is included in at least one example ofthe present technology. Thus, the occurrences of the phrases “in oneexample,” “in an example,” “one embodiment,” or “an embodiment” invarious places throughout this specification are not necessarily allreferring to the same example. Furthermore, the particular features,structures, routines, steps, or characteristics may be combined in anysuitable manner in one or more examples of the technology. The term“light” broadly connotes any wavelength or wavelength band in theelectromagnetic spectrum, including, without limitation, visible light,ultraviolet radiation, and infrared radiation. Similarly, photometricterms such as “illuminance,” “luminous flux,” and “luminous intensity”extend to and include their radiometric equivalents, such as“irradiance,” “radiant flux,” and “radiant intensity.” As used herein,the terms “substantially,” “approximately,” and “about” mean±10%, and insome embodiments, ±5%. The term “consists essentially of” meansexcluding other materials that contribute to function, unless otherwisedefined herein. Nonetheless, such other materials may be present,collectively or individually, in trace amounts.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like reference characters generally refer to the sameparts throughout the different views. Also, the drawings are notnecessarily to scale, emphasis instead generally being placed uponillustrating the principles of the invention. In the followingdescription, various embodiments of the present invention are describedwith reference to the following drawings, in which:

FIG. 1 is a graph of emission and excitation spectra of an exemplary LEDand phosphor;

FIGS. 2A and 2B are, respectively, cross-sectional and bottom schematicsof a white die in accordance with various embodiments of the invention;

FIG. 3 is a flow chart of a technique for forming a white die inaccordance with various embodiments of the invention;

FIGS. 4A-4E are cross-sectional schematics of process steps utilized tofabricate white dies in accordance with various embodiments of theinvention;

FIG. 5 is a cross-sectional schematic of a white die in accordance withvarious embodiments of the invention;

FIG. 6 is a flow chart of a technique for fabricating binned white dieshaving similar characteristics in accordance with various embodiments ofthe invention;

FIG. 7 is a schematic illustration of binned white dies having similarcharacteristics in accordance with various embodiments of the invention;

FIGS. 8A-8D are cross-sectional schematics of process steps utilized tofabricate white dies in accordance with various embodiments of theinvention;

FIGS. 9A-9F are cross-sectional schematics of white dies in variousstages of manufacture in accordance with various embodiments of theinvention;

FIGS. 10A-10D and 11 are cross-sectional schematics of process stepsutilized to fabricate white dies in accordance with various embodimentsof the invention;

FIGS. 12A-12F are cross-sectional schematics of white dies in accordancewith various embodiments of the invention;

FIGS. 13A-13G are cross-sectional schematics of process steps utilizedto fabricate white dies in accordance with various embodiments of theinvention;

FIGS. 14A-14C are cross-sectional schematics of white dies in accordancewith various embodiments of the invention;

FIGS. 15A-15E are cross-sectional schematics of process steps utilizedto fabricate white dies in accordance with various embodiments of theinvention;

FIGS. 15F and 15G are cross-sectional schematics of white dies inaccordance with various embodiments of the invention;

FIGS. 16A-16C are a schematic cross-sectional schematic (FIG. 16A) andschematic bottom views (FIGS. 16B and 16C) of white dies in accordancewith various embodiments of the invention;

FIGS. 17A and 17B are, respectively, a cross-sectional schematic and aplan-view schematic of a light-emitting element utilized in white diesin accordance with various embodiments of the invention;

FIG. 17C is a cross-sectional schematic of a light-emitting elementutilized in white dies in accordance with various embodiments of theinvention;

FIG. 18 is a cross-sectional schematic of a white die incorporating thelight-emitting element of FIGS. 17A and 17B;

FIG. 19 is a chromaticity diagram in accordance with various embodimentsof the invention;

FIG. 20 is a cross-sectional schematic of a feedback-controlled phosphordispensing system in accordance with various embodiments of theinvention;

FIGS. 21 and 22 are cross-sectional schematics of leveling systems forthe fabrication of planar white dies in accordance with variousembodiments of the invention;

FIGS. 23A and 23B are cross-sectional schematics of white dies inaccordance with various embodiments of the invention;

FIGS. 24A-24C are cross-sectional schematics of process steps utilizedto fabricate white dies in accordance with various embodiments of theinvention;

FIGS. 25 and 26 are cross-sectional schematics of white dies inaccordance with various embodiments of the invention;

FIG. 27 is a cross-sectional schematic of a lighting system utilizingwhite dies in accordance with various embodiments of the invention;

FIG. 28 is a plan-view schematic of a lighting system utilizing whitedies in accordance with various embodiments of the invention;

FIG. 29 is a cross-sectional schematic of a tilted mold utilized tofabricated white dies in accordance with various embodiments of theinvention;

FIG. 30 is a cross-sectional schematic of a system for fabricating whitedies with different thicknesses of phosphor with feedback-based controlin accordance with various embodiments of the invention;

FIGS. 31A-31C are cross-sectional schematics of process steps utilizedto treat portions of a substrate for reduced adhesion to phosphor inaccordance with various embodiments of the invention;

FIGS. 32A and 32B are cross-sectional schematics of process stepsutilized to fabricate white dies in accordance with various embodimentsof the invention;

FIGS. 33A and 33C are cross-sectional schematics of structures formedduring fabrication of white dies utilizing release materials inaccordance with various embodiments of the invention;

FIGS. 33B and 33D are cross-sectional schematics of white diesfabricated from the structures of FIGS. 33A and 33C, respectively;

FIG. 34 is a cross-sectional schematic of light-emitting elements on asubstrate composed of materials having different levels of adhesion inaccordance with various embodiments of the invention;

FIGS. 35A and 35B are cross-sectional schematics of light-emittingelements disposed on compressible substrates in accordance with variousembodiments of the invention;

FIG. 36 is a cross-sectional schematic of light-emitting elements on asubstrate patterned to control die relief of white dies incorporatingthe light-emitting elements in accordance with various embodiments ofthe invention;

FIGS. 37 and 38 are cross-sectional schematics of light-emittingelements on substrates with through-holes for application of vacuum inaccordance with various embodiments of the invention;

FIGS. 39A and 39B are cross-sectional schematics of white dies inaccordance with various embodiments of the invention;

FIGS. 40A-40D are cross-sectional schematics of process steps utilizedto fabricate white dies in accordance with various embodiments of theinvention;

FIGS. 40E and 40F are cross-sectional schematics of white dies eachincorporating multiple light-emitting elements in accordance withvarious embodiments of the invention;

FIGS. 41A and 41B are cross-sectional schematics of white diesfabricated with a shaped blade in accordance with various embodiments ofthe invention;

FIGS. 42A-42D are cross-sectional schematics of white dies in accordancewith various embodiments of the invention;

FIG. 43 is a cross-sectional schematic of a white die incorporating areflecting layer in accordance with various embodiments of theinvention;

FIG. 44 is a cross-sectional schematic of a processing step utilized tofabricate the white die of FIG. 43 in accordance with variousembodiments of the invention;

FIGS. 45A-45C are cross-sectional schematics of process steps utilizedto fabricate white dies with reflecting films in accordance with variousembodiments of the invention;

FIGS. 46A-46C are cross-sectional schematics of white dies incorporatingoptical elements in accordance with various embodiments of theinvention;

FIGS. 47A and 47B are cross-sectional schematics of process stepsutilized to fabricate the white die for FIG. 46A in accordance withvarious embodiments of the invention;

FIG. 48 is a cross-sectional schematic of a processing step utilized tocouple optical elements to a white wafer of white dies in accordancewith embodiments of the invention;

FIGS. 49A-49E are cross-sectional schematics of clear dies in accordancewith various embodiments of the invention;

FIGS. 50 and 51 are cross-sectional schematics of lighting devicesincorporating white dies and optical elements in accordance with variousembodiments of the invention;

FIGS. 52 and 53 are cross-sectional schematics of components of thelighting device of FIG. 51;

FIG. 54 is a cross-sectional schematic of a lighting deviceincorporating white dies and optical elements in accordance with variousembodiments of the invention;

FIG. 55 is a cross-sectional schematic of a component of the lightingdevice of FIG. 54;

FIG. 56 is a cross-sectional schematic of an optic utilized in lightingdevices in accordance with various embodiments of the invention;

FIG. 57 is a cross-sectional schematic of a lighting deviceincorporating the optic of FIG. 56 in accordance with variousembodiments of the invention;

FIGS. 58A-58C are cross-sectional schematics of light-detecting devicesin accordance with various embodiments of the invention;

FIGS. 59A and 59B are cross-sectional schematics of photovoltaic devicesin accordance with various embodiments of the invention;

FIGS. 60A-60E are cross-sectional schematics of electronic devices inaccordance with various embodiments of the invention; and

FIGS. 61 and 62 are cross-sectional schematics of packaged systemsincorporating multiple devices in accordance with various embodiments ofthe invention.

DETAILED DESCRIPTION

Embodiments of the present invention provide a new approach tointegration of phosphor and light-emitting elements, such as LED dies,that addresses a number of the deficiencies and difficulties present inthe current manufacture of white packaged LEDs. Advantageously, thephosphor may be integrated with a die before it is placed in a package(or instead of being conventionally packaged), thereby producing apackage-free white die. An example is depicted as white die 200 in FIG.2A. White die 200 includes one or more LEEs 210, each of which featuresat least one contact 220. As shown, the LEE 210 is partially surroundedby a phosphor 230. At least a portion of contact(s) 220 is typically notcovered by phosphor 230. In the configuration shown in FIG. 2A, LEE 210features two contacts 220 that are situated on the same face or side 240of LEE 210. As shown, each of the contacts 220 preferably has a freeterminal end that is not covered by the phosphor 230 and that isavailable for electrical connection. Herein, “available for electricalconnection” means the contact has sufficient free area to permitattachment to, e.g., a conductive trace, a circuit board, etc, and“free” means lacking any electrical connection (and in preferredembodiments, any mechanical connection) thereto.

While face 240 of LEE 210 is shown as being a single planar surface,this is not a limitation of the present invention, and in otherembodiments face 240 is composed of multiple non-coplanar surfaces ormay have other configurations. In some embodiments LEE 210 has more thantwo contacts 220. White die 200 is shown in FIG. 2A as having nophosphor 230 covering face 240; however, this is not a limitation of thepresent invention, and in other embodiments phosphor 230 covers all or aportion of face 240. As discussed above, here phosphor may refer to abinder or matrix material alone or a mixture of the binder andwavelength-conversion material. In FIG. 2A, the width of phosphor 230around the sides of LEE 210 is identified as a width 250, while thethickness of phosphor 230 over LEE 210 is identified as a thickness 260and the thickness of phosphor 230 adjacent to LEE 210 is identified as athickness 270.

FIGS. 2A and 2B show white die 200 including one LEE 210; however, thisis not a limitation of the present invention, and in other embodimentswhite die 200 includes more than one LEE 210. In some embodiments,multiple LEEs 210 of a single white die 200 are all the same, while inother embodiments they are made up of at least two different types ofLEE 210. In one embodiment, different types of LEE 210 emit at differentwavelengths. For example, white die 200 may include one or more of eachof three different types of LEE 210, where at least one type emits inthe blue wavelength range, at least one in the green wavelength rangeand at least one in the red wavelength range. In one embodiment whitedie 200 may include one or more of each of two different types of LEE210, where at least one type emits in the blue wavelength range and atleast one in the red wavelength range. The specific configuration of theLEE 210 in white die 200 as well as their operating characteristics andproperties are not a limitation of the present invention. In oneembodiment, different types of LEE 210 have different light outputpowers. In one embodiment, phosphor 230 may be composed of a pluralityof portions or volumes, where each portion or volume includes orconsists essentially of one or more phosphors different from one or morephosphors in another portion. In one embodiment of this example, one ormore portions include or consist essentially of only a transparentbinder material, while one or more other portions include or consistessentially of a binder and one or more phosphors.

In some embodiments, a surface 280 of phosphor 230 is parallel orsubstantially parallel to a surface 242 of LEE 210. In some embodiments,a surface 290 of phosphor 230 is parallel or substantially parallel to asurface 244 of LEE 210. In some embodiments phosphor 230 forms asubstantially cubic or rectangular-solid shape (the contour of which maybe broken by portions of the LEE 210 and/or the contacts of the LEE210). The thickness 260 of phosphor 230 over LEE 210 is shown as thesame or substantially the same over the entirety of LEE 210; however,this is not a limitation of the present invention and in otherembodiments thickness 260 of phosphor 230 over LEE 210 varies. Thethickness 270 of phosphor 230 adjacent to LEE 210 is shown as the sameor substantially the same for white die 200; however, this is not alimitation of the present invention and in other embodiments thickness270 of phosphor 230 adjacent to LEE 210 varies. FIG. 2A shows surface280 and side surfaces 290 of phosphor 230 as flat or substantially flat;however, this is not a limitation of the present invention and in otherembodiments surface 280 and/or surface 290 are curved, roughened,patterned, or textured in a regular, periodic, or random pattern. Insome embodiments phosphor 230 has, at least in part, a smooth,substantially continuous shape. In some embodiments, shaping and/orpatterning or texturing of the surface is achieved during the formationor molding process, while in other embodiments shaping and/or patterningor texturing is performed after the phosphor is molded or after it iscured or partially cured.

FIG. 2B shows a view of the white die 200 facing the contact side of LEE210. LEE 210 in FIG. 2B is shown as rectangular in cross-section, butthis is not a limitation of the present invention and in otherembodiments LEE 210 is square, hexagonal, circular, triangular or anyarbitrary shape and/or may have sidewalls forming any angle with respectto the surface 280 of white die 200. In FIG. 2B width 250 of phosphor230 on the sides of LEE 210 is shown as the same or substantially thesame on all sides of LEE 210; however, this is not a limitation of thepresent invention and in other embodiments width 250 of phosphor 230 isdifferent on one or more or all sides of LEE 210. FIG. 2B shows width250 of phosphor 230 as the same or substantially the same across eachside of LEE 210; however, this is not a limitation of the presentinvention, and in other embodiments width 250 of phosphor 230 variesalong one or more sides of LEE 210.

As discussed above, embodiments of the present invention form phosphor230 on LEE 210 prior to attachment (electrical and/or mechanical) to apackage or to a substrate. White die 200 may then be integrated in avariety of packages, as discussed below. FIG. 3 shows a flow chart of aprocess 300 for forming white die 200. Process 300 is shown having sixsteps; however, this is not a limitation of the present invention and inother embodiments the invention has more or fewer steps and/or the stepsmay be performed in different order. In step 310, a first surface orbase is provided. In step 320, one or more LEEs are placed or formed onthe base. In step 330, the phosphor is provided. In step 340, thephosphor is formed over the LEE and base. In step 350, the phosphor iscured. In step 360, the phosphor-coated LEEs are separated or singulatedinto white dies 200. Various approaches to using white dies 200 arediscussed below.

FIGS. 4A-4E depict one embodiment of process 300. In this embodiment, abase 410 is provided (step 310) and LEEs 210 are placed on or adhered tobase 410 (step 320) with contacts 220 adjacent to base 410 (FIG. 4A).Base 410 may also be referred to as a “mold substrate.” In oneembodiment, base 410 includes or consists essentially of an adhesivefilm or tape. In some embodiments, base 410 includes or consistsessentially of a material to which has a relatively low adhesion tophosphor 230, that is, it permits removal of cured phosphor 230 frombase 410. In some embodiments, base 410 is the same as or similar todicing or transfer tapes used in the semiconductor industry forsingulation and/or transfer of dies, for example Revalpha from NittoDenko Corporation or tapes from Semiconductor Equipment Corporation. Insome embodiments, base 410 includes or consists essentially of awater-soluble material or adhesive, or may be covered or be partiallycovered with a water-soluble material. For example, the adhesive of base410 or the liner or both may be water soluble. In some embodiments, thewater-soluble material includes or consists essentially of awater-soluble tape, for example 3M type 5414. In some embodiments base410 includes or consists essentially of a silicone or a silicone-basedmaterial, for example PDMS or GelPak material from the Gel-PakCorporation.

In some embodiments, base 410 includes or consists essentially of amaterial with variable adhesive force. In this embodiment the adhesiveforce may be changed after formation and curing of the phosphor, to makeit easier to remove the white die or white die wafer from base 410. (Awhite die wafer, also referred to as a composite wafer, is hereindefined as a plurality of semiconductor dies suspended in a binder.) Inone embodiment such a variable adhesive force material may be a thermalrelease tape or a UV release tape. In one embodiment the variableadhesive force material may be a water-soluble tape. In one embodimentthe variable adhesive force material may be an electrostatic chuck (LEEs210 are formed or placed on the electrostatic chuck, similar to thestructure shown in FIG. 4A). In this embodiment LEE 210 are held inplace on the electrostatic chuck by electrostatic forces that may beactivated or deactivated electrically.

In some embodiments, it is desirable for all or a portion of the face ofcontact 220 to be exposed after formation of white die 200, that is, tonot be covered by phosphor 230. In some embodiments, placing or adheringall or a portion of the face of contact 220 adjacent to base 410prevents coverage or formation of phosphor 230 over all or a portion ofcontact 220 or over all or a portion of the face of contact 220. In someembodiments, the thickness, hardness and/or other properties of acoating on base 410, or the properties of base 410, for example anadhesive thickness, chemical composition, surface energy, hardness,elasticity, etc., may be varied to ensure the desired level of exposureof contacts 220, for example by proximity to base 410 or partial or fullembedding of contacts 220 into base 410.

In some embodiments, base 410 includes or consists essentially of asurface or a mold (e.g., a non-flat surface). In one embodiment,barriers 450 are formed by a recess in base 410. In FIG. 4B barriers 450are shown as perpendicular or substantially perpendicular to a surface435; however, this is not a limitation of the present invention, and inother embodiments barriers 450 form any angle with surface 435. Base 410may include or consist essentially of one or more of a variety ofmaterials, for example glass, PET, PEN, plastic film, tape, adhesive onplastic film, metal, acrylic, polycarbonate, polymers, silicone,polytetrafluoroethylene (Teflon), or the like. In some embodiments, base410 is rigid or substantially rigid, while in others base 410 isflexible. In some embodiments, it is advantageous for base 410 toinclude or consist essentially of a “non-stick” material such as Teflon,or a fluorinated material such as Fluon ETFE produced by Asahi Glass orto include a non-stick coating over the surface or portion of thesurface that may come in contact with phosphor 230 (for example thebinder in phosphor 230) so that phosphor 230 does not stick to base 410.In some embodiments, base 410 includes or consists essentially of alayer of material on surface 435 and/or barriers 450 that does notadhere well to the binder material. In some embodiments, base 410includes or consists essentially of a water-soluble material oradhesive, or base 410 is partially or completely lined with awater-soluble material to aid in the release of base 410 from thematerial formed in base 410. In one embodiment, base 410 includes orconsists essentially of or is partially or fully lined with awater-soluble tape, for example 3M type 5414. In some embodiments, base410 is transparent to light, for example to visible or UV radiation. Insome embodiments, the height of barrier 450 ranges from about 10 μm toabout 1000 μm; however, the height of barrier 450 is not a limitation ofthe present invention, and in other embodiments barrier 450 has anyheight. In some embodiments, the area of base 410 is in the range ofabout 0.25 mm² to about 900 cm²; however, the area of base 410 is not alimitation of the present invention, and in other embodiments the areaof base 410 is smaller or larger. When barrier 450 is not a part of base410, barrier 450 may include or consist essentially of a materialsimilar to that or different from that of base 410. In some embodiments,barrier 450 may be a ring or stencil surrounding LEE 210.

The spacing between adjacent LEEs 210 identified as a spacing 405 inFIG. 4A may be adjusted to control the width of phosphor 230 around thesides of LEEs 210. In one embodiment, spacing 405 between LEEs 210 isapproximately determined by the sum of twice the desired sidewallthickness 250 of the phosphor and the kerf (where the kerf is the widthof the region removed during the singulation process of white dies 200,for example identified as kerf 470 in FIG. 4D). In other embodiments, asdiscussed herein, the spacing 405 is independent of the amount ofphosphor 230 surrounding LEEs 210. The thickness of phosphor 230 overthe LEEs 210 may be controlled by controlling a thickness 425 ofphosphor 420 that is formed or dispensed. In one embodiment, thickness260 of phosphor 230 over LEE 210 is given approximately by the thickness425 less the thickness 445.

The next step (step 330) in process 300 provides a phosphor (uncured orpartially cured phosphor 420). In one embodiment, phosphor 420 includesor consists essentially of a phosphor and a binder. In some embodiments,the phosphor and binder are mixed prior to application, for example in acentrifigual mixer, with or without a partial vacuum over the mixture.

In the next step (step 340) in process 300, phosphor 420 is formed overbase 410 and LEEs 210 as shown in FIG. 4B. In some embodiments, phosphor420 is contained or bounded by surface 435 of base 410 and optionalsides or barriers 450 as shown in FIG. 4B. In this example phosphor 420has a bottom surface or face 460 and a top surface or face 440. In someembodiments surfaces 460 and 440 are substantially parallel to eachother. In some embodiments surfaces 460 and 440 are substantially flatand parallel.

Phosphor 420 may be formed by a variety of techniques, for examplecasting, dispensing, pouring, injecting, injection, compression,transfer or other forms of molding, Mayer bar or draw-down bar, doctorblade, etc. The method of formation of phosphor 420 is not a limitationof the present invention. In some embodiments, base 410 is positionedsuch that surface 435 is level, such that when phosphor 420 is formed onbase 410, surface 435, bottom surface 460 of phosphor 420 and topsurface 440 of phosphor 420 are parallel or substantially parallel,forming a thin layer of phosphor 420 that has a uniform or substantiallyuniform thickness across all or most of the area of phosphor 420. Insome embodiments, one or more barriers 450 are used to prevent orpartially prevent the spread of phosphor 420. In some embodiments,surface 435 and barriers 450 form a mold for phosphor 420. In someembodiments, barriers 450 are portions of a separate component placedover base 410 surrounding LEEs 210. In some embodiments, barriers 450are not used. Some embodiments of the present invention utilize a levelbase 410 and gravity to automatically produce phosphor layer 420 with auniform or substantially uniform thickness. In one embodiment, thethickness uniformity of phosphor 420 is within about ±15%, within about±10%, within about ±5% or within about ±1% or less. In one embodiment,phosphor 420 has a thickness in the range of about 5 μm to about 2000μm; however, the thickness of phosphor 420 is not a limitation of thepresent invention, and in other embodiments phosphor 420 is thinner orthicker.

In one embodiment, the time between mixing phosphor 420 including orconsisting essentially of binder and phosphor powder and formingphosphor 420 over base 410 is relatively short compared to the timerequired for settling of the powder in the binder, such that thephosphor and binder form a uniform and homogeneously distributed orsubstantially uniform and homogeneously distributed combination ofphosphor powder in the binder. In one embodiment, the compositionaluniformity of phosphor 420, that is the distribution of phosphor powderin the binder, is uniform to within about ±15%, within about ±10%,within about ±5% or within about ±1%. In some embodiments of mixtures ofphosphor and powder, settling starts to occur within about 10 to about30 minutes, while formation of phosphor 420 in over base 410 occurswithin about 0.25 minute to about 5 minutes. In some embodiments, thestructure shown in FIG. 4B is exposed to a partial vacuum to degas orremove all or a portion of any dissolved gases in phosphor 420, toreduce or eliminate the number of bubbles in phosphor 420. In someembodiments, phosphor 420 is exposed to a partial vacuum beforeformation on base 410. In some embodiments, phosphor 420 is formed overbase 410 in a partial vacuum. In some embodiments of the presentinvention, base 410 is not level, resulting in phosphor 420 having anon-uniform thickness over base 410 and LEE 210, as discussed herein inmore detail.

Phosphor 420 is then cured, producing cured phosphor 230 (step 350) asshown in FIG. 4C. Curing may include or consist essentially of heating,exposure to radiation of various sources, for example visible, UV and/orIR light, or chemical curing (i.e., introduction of a chemical agentthat promotes cross-linking of the phosphor binder). In one embodiment,phosphor 420 is cured by UV or other radiation. In one embodiment, base410 is held within the curing equipment prior to or just after step 350of FIG. 3. In some embodiments of mixtures of binder and powder,settling starts to occur within about 10 to about 30 minutes, whilecuring of phosphor 420 over base 410 occurs within about 0.10 minute toabout 5 minutes. In one embodiment, steps 340 and 350 may take less thanabout 30 minutes, less than about 10 minutes, less than about 5 minutesor less than about 1 minute. In some embodiments the curing step 350includes or consists essentially of multiple sub-curing steps. Forexample, a first sub-curing step may be performed to “freeze” thephosphor particles in the matrix and this may be followed by a secondsub-curing step to fully cure the binder. In some embodiments both theformation and curing process may occur within about 0.25 minute to about7 minutes. In some embodiments both the formation and curing process maytake less than about 4 minutes.

In step 360 from FIG. 3, white dies 200 are separated or singulated fromthe structure shown in FIG. 4C (i.e., a white wafer, white die wafer, orcomposite wafer), resulting in the structure shown in FIG. 4D. WhileFIG. 4D shows each white die 200 including one LEE 210, this is not alimitation of the present invention and in other embodiments white die200 includes more than one LEE 210. White dies 200 may have a sizeranging from about 0.25 mm to about 5 mm; however, the size of whitedies 200 is not a limitation of the present invention. For example, awhite die including a large array of LEEs 210 may have a lateraldimension of at least 3 mm or at least 7 mm or at least 25 mm. For somewhite dies 200, separation may be optional, for example in the case oflarge arrays of LEEs 210. Separation of phosphor 230 may be performed bya variety of techniques, for example laser cutting, cutting with aknife, die cutting, dicing, saw cutting, water jet cutting, ablation, orthe like. In some embodiments, the kerf may be below about 200 μm orbelow about 100 μm or below about 50 μm or even below 25 um. Thispermits very large arrays of white dies 200 to be formed in a relativelysmall area with relatively high throughput and relatively low cost. Themolding process leads to very uniform phosphor thickness, resulting inuniform optical characteristics. The ability to form a very large numberof white dies 210 from a relatively small area of phosphor, in arelatively short time, to avoid or minimize settling of the phosphorpowder in the binder, coupled with the relatively high thicknessuniformity, leads to very large arrays of white dies 210 havingrelatively narrow distribution of optical characteristics, such aschromaticity, color temperature, color rendering index (CRI), luminousflux, etc. and very low manufacture cost. In one embodiment, an entirewafer of LEE 210 may be batch processed simultaneously using thisapproach. For example LEE 210 may be produced on a 2″ or 4″ or 6″diameter wafer. After LEEs 210 are fabricated and singulated (heresingulation refers to singulation of the substrate on which LEE 210 areformed), they may be transferred to mold substrate 410 for the white dieprocess detailed herein. In some embodiments the entire wafer amount ofLEE 210 may be transferred in batch mode (i.e., together) to moldsubstrate 410. In other embodiments LEE 210 may be transferred to moldsubstrate 410 die-by-die or in groups of dies.

In some embodiments, separation (i.e., of the white dies) takes placebefore removal from base 410 while in other embodiments base 410 isremoved before separation, as discussed in more detail herein. In someembodiments, phosphor 230 includes or consists essentially of only atransparent binder that is transparent to a wavelength of light emittedby LEE 210.

In some embodiments, the structure shown in FIG. 4D may be transferredto another substrate 411 such that contacts 220 are accessible, as shownin FIG. 4E. Such a transfer may be performed using transfer tape, apick-and-place tool with a die flipper or any other technique. In someembodiments this transfer may be done in batch mode, while in otherembodiments it may be done die-by-die or in groups of dies. In someembodiments the transfer may be performed before singulation of thewhite die wafer. The result of this process is a white die 200, as shownin FIGS. 2A and 2B. The process provides a batch method to produce diesintegrated with phosphor, with uniform phosphor over each die, in acost-effective way, before the dies are placed or integrated into anykind of package or onto a circuit board.

White dies 200 may then be removed from base 410 for placement in apackage. In some embodiments, white dies 200 may be used as is, withouta package, for example by mounting on a flexible or rigid circuit orwiring board or in other lighting of illumination systems. White dies200 may be placed in different orientations, for example those shown inFIG. 4D or FIG. 4E.

In one embodiment, only one phosphor 420 is used; however, this is not alimitation of the present invention, and in other embodiments aplurality of phosphors are used. In one embodiment, phosphor 420 mayinclude or consist essentially of a plurality of different phosphorpowders. In one embodiment, a first phosphor 420 is deposited and curedor partially cured, followed by the deposition and curing of one or moresuccessive phosphors. In one embodiment, a binder is deposited and curedor partially cured, and the binder is transparent to a wavelength oflight emitted by LEE 210 and/or phosphor 420 or 230, followed by thedeposition and curing of one or more phosphor 420, to form a layeredstructure in which one or more layers have a phosphor composition, typeand/or thickness different from each other. In this way, aremote-phosphor white die 400 may be fabricated, as shown in FIG. 5.FIG. 5 shows one embodiment of a remote phosphor white die 500, in whichphosphor 230 is spatially separated from LEE 210 by a transparent binderor matrix material 510. In such a structure the extent of the overhangof the phosphor containing layer(s) 230 past the edges of LEE 210 may bevaried to optimize the amount of light from LEE 210 that is absorbed byphosphor 230. Such an approach may also be used to form multiple layersof phosphor and/or transparent binder of LEE 210.

The following examples present some embodiments of the presentinvention. However these are not limiting to the method of manufactureor structure of the white die.

Example 1

In this example LEEs 210 are fabricated in wafer form (i.e., as portionsof a semiconductor wafer). A wafer may include about 5000 or more LEEs210. In some embodiments, a wafer includes over about 20,000, over100,000, or over 500,000 LEEs 210. After fabrication of LEEs 210, LEEs210 are tested and sorted into bins, as shown in steps 610, 620 of FIG.6. Bins may include, for example emission wavelength, forward voltage,light output power or the like. The particular choice of one or morebins or range of values within the one or more bins is not a limitationof the present invention. In one embodiment, LEEs 210 are binned byemission wavelength. The process shown in FIG. 3 may then carried out oneach bin of LEEs 210. The composition and amount of phosphor appliedover base 410 and LEE 210 is determined in advance to achieve thedesired color point, chromaticity, color temperature, CRI or otheroptical properties, based on the emission wavelength of each bin. Inthis embodiment, each bin may have a different composition and/orthickness of phosphor to achieve the desired optical properties. In oneembodiment, the phosphor composition and thickness are adjusted based onthe bin information to achieve a relatively more narrow distribution inoptical properties (for example color temperature) than would beachievable without binning.

For example, in FIG. 7, wafer 710 represents a wafer containing thetotal distribution of characteristics from fabricated LEEs 210 from awafer or growth run or series of growth runs as well as one or moreprocess runs. During the growth or deposition process for the epitaxialstructure, and subsequent fabrication steps to form LEEs 210, variationin optical and electrical properties may be introduced. LEEs 210 aretested and sorted into bins, where each bin has a relatively narrowdistribution of one or more characteristics. For example, wavelengthbins may have about 5 nm or about 2.5 nm distributions. Other examplesof bins include forward voltage and light output power. Bins 720, 730and 740 represent different bins, for example three different wavelengthbins. In FIG. 7, the boxes representing bins 720, 730 and 740 have asmall graph representing the distribution of dies with a particularcharacteristic in that bin. While three bins are shown in FIG. 7, thisis not a limitation of the present invention, and in other embodimentsfewer or more than three bins are utilized. LEEs 210 from each bin,designated 210′, 210″ and 210′ are used to determine the characteristicsof phosphor 230 (i.e., to achieve a final optical characteristic of theLEE and phosphor combination), resulting in a corresponding number ofdifferent phosphor mixes, identified as 230′, 230″ and 230′. Thisresults in a corresponding number of bins of white die 200, designated200′, 200″ and 200′. In this way a relatively larger percentage of thedistribution of LEEs 210 from the entire manufacturing process may befabricated into white dies 200 having a relatively narrow distributionof optical characteristics, for example color temperature.

A flow chart of this process is shown in FIG. 6. The LEEs 210 are firsttested (step 610) and then sorted and separated into bins (step 620).One bin of LEEs 210 is chosen (step 630) and a phosphor is prepared toachieve the desired optical properties for that particular bin of LEEs210 (step 640). This phosphor may include or consist essentially of oneor more phosphor powders or light-conversion materials. Finally, in step650, process 300 shown in FIG. 3 is carried out using the selected binof LEEs 210 and phosphor prepared for that bin of LEEs 210. This may berepeated for the other bins.

Example 2

In this example LEEs 210 are fabricated in wafer form. A wafer mayinclude over about 5000 or more LEEs 210. In some embodiments, a wafermay include over about 20,000 or over 100,000 LEEs 210. Afterfabrication of LEEs 210, LEEs 210 are tested, or some of LEEs 210 oneach wafer are tested. In one embodiment, the process shown in FIG. 3 isthen carried out on all LEEs 210 from the wafer. The composition andamount of phosphor applied over base 410 and LEE 210 is determined inadvance to achieve the desired color point, color temperature, CRI orother optical properties, based on the test results of LEE 210 on thatwafer. This phosphor may include or consist essentially of one or morephosphor powders or light-conversion materials.

In one embodiment of this example, there is no testing done on LEEs 210prior to formation of the phosphor over LEEs 210. In one embodiment ofthis example, the starting wafer is applied to dicing tape, after whichthe wafer is singulated into LEEs 210. The tape has the ability toexpand and is expanded to provide the required spacing between LEE 210to achieve the desired size phosphor over LEEs 210. In one embodimentthe spacing between LEEs 210 is approximately given by the sum of twicethe sidewall thickness of the phosphor (thickness of the phosphor on theside of LEE 210) and the kerf. An example of such an expansion tape isSWT20+ manufactured by Nitto Denko.

If the singulation is performed with the contacts down on the tape, thetape may be used as base 410. If the singulation is performed with thecontacts up (not adjacent to the tape), LEEs 210 may be transferredusing transfer tape or other transfer methods. In the tape-transferoperation a second substrate or tape is applied to the exposed side(here contact side) of LEEs 210 and the first tape is removed. A varietyof techniques may be used for such transfer, for example using tapes ofdifferent tack levels, thermal release tape and/or UV release tape. Anadvantage of this approach is that LEEs 210 are then positionedcorrectly on base 410 without any need for a serial pick-and-placeprocess, saving time and money. In another embodiment, LEEs 210 may beplaced on base 410 at the correct spacing, using semi-batch or serialtechniques, for example pick-and-place.

FIGS. 8A-8D depict a schematic of one embodiment of this process. InFIG. 8A, tape 820 is applied to the back of wafer 810 (in this examplethe contacts are face up). FIG. 8B shows the structure of FIG. 8A at alater stage of manufacture. In FIG. 8B wafer 810 has been singulated,resulting in LEEs 210 on tape 820. The spacing 830 between LEE 210 isdetermined by the singulation process. In some embodiments, spacing 830is in the range of about 15 μm to about 100 μm. FIG. 8C shows thestructure of FIG. 8B at a later stage of manufacture. In FIG. 8C, tape820 has been optionally expanded or stretched. Space 830, identified asspace 830′ after expansion, is set to the correct value for making whitedies, as described above, by the expansion process. That is, tape 820 isexpanded until the spacing between adjacent LEEs 210 is appropriate tomake white dies 200 having a desired thickness of phosphor thereon. FIG.8D shows the structure of FIG. 8C at a later stage of manufacture. InFIG. 8D a second tape 840 is applied to the contact side of LEE 210.Finally, first tape 820 is removed, leaving the structure shown in FIG.4A, whereupon the process described above in FIG. 3 and shown in FIGS.4A-4D may be carried out. In some embodiments, tape 840 is the base ormold substrate 410 shown in FIG. 4A.

Example 3

In this embodiment, the process starts with the structure shown in FIG.4C or FIG. 4D. In some embodiments of this example, LEEs 210 have beenbinned, while in other embodiments LEEs 210 have not been binned or mayhave not been tested. In some embodiments of this example some of LEEs210 have been tested. The process by which the structure shown in FIG.4C is formed is not a limitation of the present invention. The structureshown in FIG. 4C may be called a white wafer or a white die wafer,featuring a plurality of LEEs 210 and phosphors 230 before singulation.The structure in FIG. 4D includes a plurality of white dies 200 on moldsubstrate 410.

White dies 200 are tested either in white wafer form (shown, forexample, in FIG. 4C) or in singulated form (shown, for example, in FIG.4D). Testing may be performed by applying a current and voltage tocontacts 220 and measuring the emitted light. In one embodiment,contacts 220 are accessed for testing by probes or needles that poke orpenetrate through tape 410. In other embodiments, testing is performedby first transferring the structure in FIG. 4C or white dies 200 in FIG.4D to another carrier such that contacts 220 are face up and directlyaccessible. Such a transfer may be performed in a batch process, similarto that using transfer tape described in conjunction with FIGS. 8A-8D,or may be performed in a semi-batch process or a serial process, such aspick-and-place. Once the structure from FIG. 4C or white dies 200 areoriented with the contacts accessible, they may be tested usingconventional test equipment, for example manual, semi-automatic or fullyautomatic test equipment that applies a current and voltage to LEEs 210,and measuring the light properties of white dies 200. In one embodiment,the white wafer of FIG. 4C or white die 200 of FIG. 4D may be processedin wafer form, similar to what is done with conventional semiconductorwafers. In this case the structures in FIGS. 4C and 4D may besufficiently rigid, or an additional backing material or plate orcarrier may be used provide additional rigidity so that the white wafermay be handled and tested in a fashion and using equipment similar tothat used for semiconductor wafers.

In one embodiment, after testing, white dies 200 are physically sortedand binned. This results in multiple bins having different opticalproperties that may then be used for different products. In oneembodiment, the bins correspond to different values of colortemperature.

In one embodiment, after testing, white dies 200 are virtually sortedand binned. In accordance with preferred embodiments, virtual sortingand binning means that a map of the characteristics of each white die200 is produced, and white dies 200 are put into, or assigned, tovirtual bins based on their optical and/or electrical properties, forexample color temperature or forward voltage. When using these virtuallybinned white dies 200 for products that require differentcharacteristics, the bin map is used to select white dies 200 from theappropriate one or more bins for that particular product. The remainingwhite dies 200 from other bins may then be used in a different productat a different time. In one embodiment, white dies 200 are used withouttesting or binning.

In any approach, if the starting point of the process is the structureshown in FIG. 4C, the structure may be singulated to form white dies 200before or after testing. Furthermore, before either physical or virtualwhite die 200 binning, the white wafers (FIG. 4C or 4D) may also bebinned, either physically or virtually.

Example 4

In one embodiment the body of LEE 210 stands above base or tape 410, asshown in FIG. 9A. After formation of the phosphor, the white diestructure may include a portion of the phosphor around and covering allor a portion of the edges of the white die, as shown in FIG. 9B. Anenlarged view of such a white die is shown in FIG. 9C. In someembodiments, base 410 is deformable or flexible such that portions ofone or more contacts 220 are embedded into tape 410, as shown forstructure 910. Structure 910 has coplanar contacts, but this is not alimitation of the present invention, and in other embodiments LEE 210has non-coplanar contacts, as shown in structures 920 and 930. In someembodiments LEEs 210 may be tilted, as shown for structure 930 in FIG.9A, resulting in a similar structure shown in FIG. 9C, but without theneed for one or more contacts 220 to be partially or substantiallyembedded into base or tape 410.

Such a structure may result in enhanced yield. The reason for this isthat the die-singulation process, i.e., where the semiconductor wafer isseparated into individual dies, may result in chipping or other damageto the passivation at the edge of the dies. If the chipping or damage tothe passivation at the edge permits exposure of underlying conductivesemiconductor material, undesirable electrical coupling to thisconductive semiconductor material may occur in the attachment process ofa white die 210, resulting in poor device performance and/or shorting ofthe device.

In some embodiments a portion of the body of LEE 210 is not covered withphosphor, as shown in FIG. 9D. FIG. 9D shows a white die 200, similar tothat shown in FIG. 2A, but with a portion of the sidewall of the body ofLEE 210 not covered in phosphor. The extent that LEE 210 extends beyondthe edge of phosphor 230 may be identified as the die relief 950. Insome embodiments the die relief is positive, as shown in FIG. 9D, but inother embodiments the die relief may be substantially zero, as shown inFIG. 2A or even negative, as shown in FIG. 9E. Another dimension thatmay be advantageously controlled is the contact relief 960. The contactrelief 960 is the amount that the contact protrudes from the adjacentsurface of the phosphor. In some embodiments the die relief may besubstantially zero and the contact relief is positive. In someembodiments both the die and contact relief are positive. The polaritiesand absolute values for the die and contact relief are not a limitationof the present invention. In some embodiments the contact relief ispositive and in the range of about 1 μm to about 15 μm.

In some embodiments it is advantageous to control the die and/or contactrelief, for example in some embodiments the variation in die and/orcontact relief is less than about 30%, or less than about 15% or lessthan about 10%. Die and/or contact relief may be controlled by a numberof different techniques. In some embodiments LEEs 210 are partiallyembedded in mold substrate 410, as shown in FIG. 9F. The amount ofrelief 970 (here relief may refer to either die or contact relief or thecombination) is then substantially determined by the size of dimension970 that LEE 210 is embedded in mold substrate 410, as shown in FIG. 9F.

Example 5

FIGS. 10A-10C depict another technique for fabricating white dies 200 inaccordance with various embodiments of the present invention. In suchembodiments LEEs 210 are attached to a mold substrate or temporarycarrier 410 with the contacts adjacent to temporary carrier 410. A mold1030 includes or consists essentially of one or more compartments,depressions, or wells 1020 into which LEEs 210 will be inserted orpartially inserted or over or under which LEEs 210 will be suspended(for example, if barriers separating the compartments do not extendsufficiently far to form fully closed compartments). In anotherembodiment wells 1020 are formed by insertion of a template into an openmold (such as that shown in FIG. 4B). Wells 1020 are filled or partiallyfilled with phosphor 420, for example by dispensing, by the doctor blademethod, stencil printing, or by other means. Following formation ofphosphor 420 in wells 1020, temporary carrier or base 410 is mated withmold 1030 such that LEEs 210 are fully or partially immersed in phosphor420, as shown in FIG. 10B. Contacts 220 are adhered to temporary carrier410, preventing phosphor 420 from covering at least a portion ofcontacts 220. In one embodiment phosphor 420 is introduced or injectedinto wells 1020 after mold 1030 is mated with base 410. In one aspect ofthis embodiment, a partial vacuum may be used to enhance transport ofphosphor 420 to all wells 1020 and to partially or fully degas phosphor420 before curing. The process may include or consist essentially ofinjection molding, transfer molding, compression molding, casing etc.Compression molding may be carried out using equipment such as a FFT-103manufactured by Towa Corporation. In some embodiments, mold 1030 isflat, i.e., effectively including only one depression 420 into whichfits multiple LEEs 210. In one embodiment, the structure of FIG. 10B isflipped, with base 410 on the bottom and mold 1030 on top, such thatphosphor 420 is formed over base 410 and LEE 210, over which a topportion 1031 of the mold 1030 is formed and in one embodiment of thisexample mold 1030 is a flat surface. For example, the structure of FIG.4B may be filled or over-filled with phosphor 420, after which a moldtop or cover 1031 is applied, as shown in FIG. 10D. The shape of mold1030 is not a limitation of the present invention and in otherembodiments mold 1030 has any shape. In some embodiments, both base 410and mold 1030 have raised barriers or sidewalls. As discussed herein, apattern, roughness or texture in all or a portion of the outer surfaceof phosphor 230 may be formed by introducing those features into thesurface of all or portions of the surface of the mold. In someembodiments, different LEEs 210 on base 410 have differently shapedphosphors formed around them.

In some embodiments all or a portion of mold 1030 is covered by a moldrelease material. In some embodiments the mold release material is amold release film. In some embodiments the mold release material or moldrelease film may be patterned, roughened or textured to, e.g., impartsimilar features on all or portions of the outer surface of phosphor230. In some embodiments the mold release material or mold release filmmay be smooth or substantially smooth.

After curing of phosphor 420 and removal from mold 1030, the structureis as shown in FIG. 10C. FIG. 10C shows white dies 200 with phosphor 230covering the sides and bottom of LEEs 210, with contacts 220 of LEEs 210adhered to temporary carrier 410 and not covered with phosphor 230. Inone embodiment, temporary carrier 410 includes or consists essentiallyof tape or film, as discussed above, from which white dies 200 may bepicked for placement in a lighting or other system. The width 250 ofphosphor 230 (FIG. 2A) around the edges or sides of LEEs 210 may becontrolled by controlling the width 1040 of depression 1020 relative tothe size of LEE 210. In one embodiment, the thickness of phosphor 230 onthe sides of LEE 210 is approximately given by one-half of thedifference between width 1040 and the width 1060 of LEE 210. (The width1060 of LEE 210 may not be constant in all dimensions.) In oneembodiment the thickness 260 of phosphor 230 (FIG. 2A) over LEE 210 maybe controlled by controlling the depth 1050 of depression 1020 relativeto the thickness of LEE 210. In one embodiment the thickness 260 ofphosphor 230 (FIG. 2A) over LEE 210 may be controlled by variousoperational parameters of the molding process, for example the amount ofphosphor present during compression molding. In some embodiments thethickness 260 of phosphor 230 (FIG. 2A) over LEE 210 is controlled bymore than one factor. In one embodiment, thickness 260 is approximatelythe depth 1050 of well 1020 less the height 445 of LEE 210 above base410 (FIG. 4B). In some embodiments where a plurality of LEEs 210 areformed in each depression, or where mold 1030 has only one depression,white die 200 may include a plurality of LEEs 210 or white die 200 maybe formed by singulation of phosphor 230. In other words, the structureshown in FIG. 4C may also be produced by a molding process.

In some embodiments, excess phosphor 420 may be squeezed out into theregion outside of the mold, for example outside of depression 1020,between base 410 and mold 1030. In one embodiment of this example, oneor more portions of the mold have one or more openings or through-holes1100 that provide an overflow pathway for phosphor 420 during the matingprocess, as shown in FIG. 11. Phosphor 420 is formed in wells 1020 asdiscussed above. When base 410 and mold 1030 are mated, hole 1100provides a pathway for excess phosphor 420 to escape, thereby permittingthe manufacture of white die 210 with wells 1020 completely orsubstantially full of phosphor, without excess phosphor squeezing outthe sides of the mold. In some embodiments, this provides improvedcontrol of the thickness of phosphor 230 as well as a more reproduciblemanufacturing process. This approach may be applied to otherembodiments, for example that shown in FIG. 10D, or in configurationswhere phosphor 420 is formed in the mold after mating of base 410 andmold 1030. As discussed previously, control of phosphor thickness 260and 270 may be very important to maintaining uniform opticalcharacteristics. In the arrangement discussed here the phosphorthickness may be controlled by the dimensions of well 1020, which isindependent of the process parameters for dispensing or forming phosphor420 in well 1020. In this embodiment a small excess of phosphor 420 isformed in well 1020, and when base 410 is brought into contact with mold1030, excess phosphor 420 may move into hole 1100. After mating of tape410 and mold 1030, phosphor 420 may be cured to form, and the amount ofphosphor over LEE 210 is controlled by the geometry of the structure,rather than by the formation or dispense parameters. In one embodiment,base 410 and mold 1130 are held together by vacuum or pressure duringall or a portion of the cure operation. In some embodiments phosphor 420is injected into the mold through holes 1100.

While FIG. 10C shows white dies 200 as completely separated after themold process, without any additional singulation process, this is not alimitation of the present invention and in other embodiments white dies200 may be connected together by a thin web of phosphor 230 as a resultof the mold process as discussed herein in reference to FIG. 12F. Insome embodiments the web may have a thickness in the range of about 5 μmto about 100 μm. In some embodiments white dies 220 may be shaped, asdiscussed below, but connected after molding, and require a subsequentsingulation process.

Example 6

Example 6 is very similar to Example 5, with the difference that well1020 in mold 1030 may be modified to have any arbitrary shape. Suchshaping may be done, for example, to improve light extraction. FIGS.12A-12D depict several embodiments of white dies 200 that may befabricated with a shaped mold. The structure of FIG. 12A has a reducedamount of phosphor over the corners of LEE 210 than over the center ofLEE 210. The structure of FIG. 12B has a non-smooth, for exampletextured, rough, or patterned, surface 1210. In one embodiment, thenon-smooth surface 1210 reduces total internal reflection (TIR) withinphosphor 230 and achieves improved light extraction. In one embodimentsurface 1210 may have a periodic structure; however, this is not alimitation of the present invention, and in other embodiments thestructure may be random. In one embodiment surface 1210 may includelight extraction features (e.g., raised bumps and/or depressions) havinga dimension in the range of about 0.5 μm to about 5 μm; however, this isnot a limitation of the present invention, and in other embodiments thelight extraction features may have other dimensions. In one embodimentthe light extraction features may be hemispherical or pyramidal inshape; however, this is not a limitation of the present invention, andin other embodiments the light extraction features may have any shape.In one embodiment the light extraction feature is a random texture orroughness with an average roughness in the range of about 0.5 μm toabout 10 μm. In the structure of FIG. 12C, the phosphor is shaped in alens shape. Such a lens may be a hemisphere, a paraboloid, a Fresneloptic or any other shape. The structure of FIG. 12D has a photoniccrystal 1220 formed on the top surface. In one embodiment, the photoniccrystal 1220 increases the intensity of light exiting white die 200 in aspecific direction, for example perpendicular to the face of white die200. In other embodiments, a photonic crystal is formed on all or aportion of any surface of white die 200. FIG. 12E shows a portion of awhite wafer having contiguous molded shapes over LEEs 210. In someembodiments this is singulated, for example at the joining line 1230 toform individual white dies 210, while in other embodiments a white die210 may include a plurality of LEEs 210 with a plurality of shapedphosphors 230, as shown in FIG. 12F. As shown in FIG. 12F, the shapedphosphors 230 may be connected by a thin region 1250. In someembodiments region 1250 may be advantageously minimized to reduce theconsumption of unused phosphor, for example by minimizing the thicknessand/or lateral extent of region 1250. However, this is not a limitationof the present invention, and in other embodiments region 1250 may haveany shape or size or may be absent, as described herein.

In one embodiment the phosphor may be shaped by forming a white die asshown in FIG. 2A or a white die wafer as shown in FIG. 4C and thenremoving one or more portions of the phosphor to produce a shapedifferent from the starting shape. Removal of one or more portions ofthe phosphor may be accomplished using a variety of means, for exampleknife cutting, dicing, laser cutting, die cutting, or the like.

Example 7

In this embodiment of the present invention, the process starts withproviding base 410, as described above. In one embodiment, base 410includes or consists essentially of a film or tape. In one embodiment,base 410 includes or consists essentially of an adhesive tape, forexample an adhesive tape where the adhesive is, for example a thermalrelease adhesive, a UV release adhesive, a water-soluble adhesive or thelike. LEEs 210 are then formed or placed on or over base 410, as shownin FIG. 13A. In this example, LEEs 210 are placed such that contacts 220are face up, i.e., not adjacent to base 410, in contrast to previousexamples in which contacts 220 were placed on base 410.

FIG. 13B shows the structure of FIG. 13A at a later stage ofmanufacture. After placing LEEs 210 on base 410, phosphor 420 isprovided, as described above, and formed over LEEs 210 and base 410. Asshown in FIG. 13B, the phosphor level is coplanar, or substantiallycoplanar with surface 1310 of LEE 210, leaving contacts 220 exposed. Inother embodiments, the phosphor level may be controlled to achieve adesired contact and/or die relief. Phosphor 420 may be formed by avariety of techniques, for example dispensing, pouring, injecting,molding, etc. The method of formation of phosphor 420 over LEEs 210 andbase 410 is not a limitation of the present invention. In someembodiments, base 410 is positioned such that a surface 1310 of the LEE210 is level, such that when phosphor 420 is formed over base 410,surface 1310 and surface 460 are parallel or substantially parallel,forming a thin layer of phosphor 420 that has a uniform or substantiallyuniform thickness across all or most of the area of phosphor 420. Insome embodiments, formation of phosphor 420 is accomplished using aMayer bar or draw-down bar, to achieve a uniform layer of phosphor 420.However it is formed, in one aspect of the present invention a levelmold and gravity are used to automatically produce phosphor layer 420with a uniform or substantially uniform thickness. In other aspects ofthis invention, the uniform or substantially uniform thickness isachieved through a molding process, as discussed above. In oneembodiment, the thickness uniformity of phosphor 420 is within about±15%, within about ±10%, within about ±5% or within about ±1%. In oneembodiment, phosphor 420 has a thickness in the range of about 1 μm toabout 2000 μm; however, the thickness of phosphor 420 is not alimitation of the present invention, and in other embodiments phosphor420 is thinner or thicker.

As shown in FIG. 13B, in one embodiment a surface 1320 of phosphor 420is coplanar or substantially coplanar with surface 1310 of LEEs 210. Inthis example phosphor 420 covers all or substantially all of thesidewalls of LEE 210. In one embodiment, phosphor 420 is formed on base410 to such a level. In another embodiment, phosphor 420 is formed overtop surface 1310 of LEE 210 and a portion of phosphor 420 (or phosphor230 after curing) is subsequently removed to provide electrical accessto contacts 220. In another embodiment, phosphor 420 is formed below topsurface 1310 of LEE 210, for example to achieve positive die relief. Inone embodiment the amount of die relief may be controlled by varying thelevel of phosphor 420 relative to top surface 1310 of LEE 210.

Phosphor 420 is then cured or partially cured, where cured phosphor isidentified as cured phosphor 230. Curing may include or consistessentially of heating, exposure to radiation of various sources, forexample visible, UV and/or IR light, or chemical curing, as discussedpreviously. In one embodiment, phosphor 420 is cured by UV or otherradiation and base 410 is transparent to such radiation.

In one embodiment, phosphor 420 includes or consists essentially of alight-cured binder. In this embodiment, phosphor 420 is initially formedto a height above that of LEE 210, as shown in FIG. 13C. Exposure ofphosphor 420 to light (exposure radiation) through the back side of LEE210, which is transparent or partially transparent to such light, (thatis the side opposite that to which LEE 210 are attached) will curephosphor 420 except for portions over contacts 220, where contacts 220are opaque or substantially opaque to such exposure radiation, as shownin FIG. 13D. The uncured phosphor 420 may then be removed, providingaccess to contacts 220 for electrical coupling, as shown in FIG. 13E.Cured phosphor 230 then covers all of LEE 210 except for opaque orsubstantially opaque contacts 220. If the surface of LEE 210 outside ofcontacts 220 is covered or partially covered with a material opaque orpartially opaque to the exposure radiation, for example with a mirror orother reflective material, then phosphor 420 that was situated above theopaque or partially opaque region will not be exposed to light and willalso be removed.

The structures shown in FIG. 13B or 13E may be used at this point orsingulated and used at this point in the process. However, thesestructures typically do not have the face opposite the contact facecovered with phosphor. This may result in undesirably high blue emissionin the spectra and/or loss of total emitted light and thus a reductionin efficiency. Several methods may be used to form white dies that aremore completely encased in phosphor. In a preferred embodiment, thestructures shown in FIG. 13B or 13E are transferred to second base 1330,for example using transfer methods described previously, such thatcontacts 220 are adjacent to second base 1330, as shown in FIG. 13F.

In some embodiments, second base 1330 is similar to or the same as base410. After this transfer process, one or more additional layers ofphosphor 420′ may be formed over the structure shown in FIG. 13F, asshown in FIG. 13G. Phosphor 420 is then cured and the dies may beseparated, as discussed above, resulting in the white die 1410, as shownin FIG. 14A. White die 1410 is similar to white die 200 shown in FIG.2A, with the difference that the encasing phosphor is formed in at leasttwo steps for white die 1410, while only one step may be required forphosphor formation of white die 200. FIG. 14A shows an example of awhite die 1410 in which both portions of phosphor 230 (cured phosphor)are the same while FIG. 14B shows an example of a white die 1410′ inwhich phosphor 230 is different from phosphor 230′. White die 1410 and1410′ in FIGS. 14A and 14B show two portions of phosphor 230 (or 230′);however, this is not a limitation of the present invention, and in otherembodiments phosphor 430 may be composed of more than two portions orlayers.

FIG. 14C shows a structure similar to those shown in FIGS. 14A and 14B,but in this case a surface 1320 of phosphor 230 is above the bottomsurface of LEE 210 to generate a positive contact relief 960.

Example 8

In this example, white die 1510 includes multiple conformal,substantially conformal or semi-conformal phosphor coatings, as shown inFIG. 15E. The process to make white dies 1510 starts with the structureshown in FIG. 15A, featuring base 410 and LEEs 210 mounted over base 410with contacts 220 adjacent to base 410. A stencil, mold, template,barrier or other structure, identified as barrier 1520 in FIG. 15B, isthen formed over base 410 in between LEEs 210. Phosphor 420 is thenformed in the regions between barriers 1520, as shown in FIG. 15B.Phosphor 420 is then cured or partially cured and barrier 1520 removed(after partial or full curing of phosphor 420) leaving the structureshown in FIG. 15C. Each of the structures in FIG. 15C is basically whitedie 210, but manufactured in a different process than described above.In another embodiment, the structure of FIG. 15C is formed in otherways, for example by starting with a structure similar to that shown inFIG. 4C and removing a portion of phosphor 230 between LEEs 210. Removalof phosphor 230 may be done by a variety of techniques, for examplecutting, laser ablation, laser cutting, etching, sandblasting or thelike. The method of removal of phosphor 230 is not a limitation of thepresent invention.

FIG. 15D shows the structure of FIG. 15C at an optional later stage ofmanufacture. In FIG. 15D, phosphor 230′ has been formed over thestructure of FIG. 15C. In some embodiments phosphor 230′ is the same asphosphor 420 or phosphor 220, while in other embodiments phosphor 230′is different from phosphor 420 or phosphor 220. Phosphor 230′ is thencured or partially cured, forming cured phosphor 230′ and resulting inthe structure of FIG. 15D. FIG. 15E shows the structure of FIG. 15D at alater stage of manufacture in which white dies 1510 are formed byseparation of phosphor 230′. FIG. 15E shows two layers or levels ofphosphor, 230 and 230′; however, this is not a limitation of the presentinvention, and in other embodiment, more than two layers or levels ofphosphor are utilized. In some embodiments, the layer of phosphorclosest to LEE 210 includes or consists essentially of a transparentbinder and no phosphor. FIG. 15E shows each layer or level of phosphorhaving substantially the same conformal shape around LEE 210; however,this is not a limitation of the present invention, and in otherembodiments the shape of each phosphor layer or level is different, forexample as shown in FIGS. 12A-12D. In some embodiments, different layersof phosphor serve different purposes, for example to improve lightextraction from LEE 210 and/or phosphor 230 or to convert light from LEE210 to a different wavelength.

While FIGS. 15A-15E show an example of multiple phosphor coatings havinga rectangular solid volume, this is not a limitation of the presentinvention, and in other embodiments multiple shaped coatings may beformed, as shown in FIG. 15F. While FIGS. 15A-15E show an example ofmultiple conformal phosphor coatings (i.e., each coating having theshape of the previous one thereunder), this is not a limitation of thepresent invention, and in other embodiments the various coatings are notconformal, as shown in FIG. 15G.

Example 9

This example uses a process similar to that discussed with reference toFIG. 4D. However, in this example, instead of one LEE 210 per white die200, this embodiment features a plurality of LEEs 210 in each white die200. FIGS. 16A-16C show several examples of white dies 1610 eachfeaturing a plurality of LEEs 210. FIG. 16A shows a cross-sectional viewof a multi-LEE white die comprising five LEEs 210. FIG. 16B shows a planview of a multi-LEE white die comprising nine LEEs 210 in a 3×3 array.FIG. 16C shows a plan view of a multi-LEE white die comprising four LEEs210 in a 1×4 array. The examples in FIG. 16A-16C show rectangular whitedies; however, this is not a limitation of the present invention, and inother embodiments the white die are square, triangular, hexagonal, roundor any other shape. The examples in FIG. 16A-16C show LEEs 210 in aregular periodic array; however, this is not a limitation of the presentinvention, and in other embodiments LEEs 210 are arrayed or spaced inany fashion.

Example 10

FIGS. 17A and 17B depict an exemplary LEE 1700 for use in an embodimentof the present invention. FIG. 17A shows a cross-sectional view whileFIG. 17B shows a top plan view of LEE 1700. LEE 1700 typically includesa substrate 1710 with one or more semiconductor layers disposedthereover. In this exemplary embodiments, LEE 1700 represents alight-emitting device such as a LED or a laser, but other embodiments ofthe invention feature one or more semiconductor dies with different oradditional functionality, e.g., processors, sensors, photovoltaic solarcells, detectors, and the like. Non-LED dies may or may not be bonded asdescribed herein, and may have contact geometries differing from thoseof LEDs. While FIGS. 17A and 17B show LEE 1700 having non-coplanarcontacts 1760 and 1770, this is not a limitation of the presentinvention and in other embodiments LEE 1700 may have coplanar orsubstantially coplanar contacts, as shown in FIG. 17C (in FIG. 17C theinternal structure for contacting the various layers is not shown forclarity).

Substrate 1710 may include or consist essentially of one or moresemiconductor materials, e.g., silicon, GaAs, InP, GaN, and may be dopedor substantially undoped (e.g., not intentionally doped). In someembodiments, substrate 1710 includes or consists essentially of sapphireor silicon carbide. Substrate 1710 may be substantially transparent to awavelength of light emitted by the LEE 1700. As shown for alight-emitting device, LEE 1700 may include first and second dopedlayers 1720, 1740, which preferably are doped with opposite polarities(i.e., one n-type doped and the other p-type doped). One or morelight-emitting layers 1730, e.g., one or more quantum wells, may bedisposed between layers 1720, 1740. Each of layers 1720, 1730, 1740 mayinclude or consist essentially of one or more semiconductor materials,e.g., silicon, InAs, AlAs, GaAs, InP, AlP, GaP, InSb, GaSb, AlSb, GaN,AN, InN, and/or mixtures and alloys (e.g., ternary or quaternary, etc.alloys) thereof. In preferred embodiments, LEE 1700 is an inorganic,rather than a polymeric or organic, device. In some embodiments,substantially all or a portion of substrate 1710 is removed prior toformation of the phosphor, as described below. Such removal may beperformed by, e.g., chemical etching, laser lift-off, exfoliation,mechanical grinding and/or chemical-mechanical polishing or the like. Insome embodiments all or a portion of substrate 1710 may be removed and asecond substrate—e.g., one that is transparent to or reflective of awavelength of light emitted by LEE 1700—is attached to substrate 1710 orsemiconductor layer 1720 prior to formation of the phosphor as describedbelow. In some embodiments substrate 1710 comprises silicon and all or aportion of silicon substrate 1710 may be removed prior to phosphorformation as described below. Such removal may be performed by, e.g.,chemical etching, laser lift off, mechanical grinding and/orchemical-mechanical polishing or the like. In some embodiments substrate1710 is used as a template for growth of the active layers of thedevice, for example layers 1720, 1730 and 1740. In some embodiments, inuse, substrate 1710 provides mechanical support but does not provide anelectrical or optical function and may be removed. In some embodimentsremoval of substrate 1710 during the formation process for the white dieincludes removal of all or a portion of substrate 1710 that does notprovide electrical functionality (e.g., does not contribute to theemission or detection of light).

As shown in FIGS. 17A and 17B, in preferred embodiments LEE 1700 ispatterned and etched (e.g., via conventional photolithography and etchprocesses) such that a portion of layer 1720 is exposed in order tofacilitate electrical contact to layer 1720 and layer 1740 on the sameside of LEE 1700 (and without, for example, the need to make contact tolayer 1720 through substrate 1710 or to make contact to layer 1720 witha shunt electrically connecting a contact pad over layer 1740 to layer1720). One or more portions of layers 1730, 1740 are removed (or neverformed) in order to expose a portion of layer 1720, and thus FIG. 17Adepicts a surface 1725 of LEE 1700 that is non-planar, i.e., containsexposed portions non-coplanar with each other. Surface 1725 correspondsto the outer surface of LEE 1700, including any contour or topographyresulting from portions of layers not being present. In order tofacilitate electrical contact to LEE 1700, discrete electrical contacts1760, 1770 are formed on layers 1740, 1720, respectively. Electricalcontacts 1760, 1770 may each include or consist essentially of asuitable conductive material, e.g., one or more metals or metal alloysconductive oxides, or other suitable conductive materials and aregenerally non-coplanar (particularly in embodiments when havingapproximately equal thicknesses), as depicted in FIG. 17A. In someembodiments surface 1725 is planar or substantially planar. In someembodiments the top surfaces of electrical contacts 1760 and 1770 arecoplanar or substantially coplanar. The structure shown in FIGS. 17A and17B is for illustrative purposes. There are a wide variety of designsfor LEE 210 or LEE 1700, and the specific design of LEE 210 or LEE 1700is not a limitation of the present invention. For example, in someembodiments LEE 210 or LEE 1700 may have different shaped contacts,different area contacts, different approaches to contact thesemiconductor material or the like.

In some embodiments, LEE 1700 has a square shape, while in otherembodiments LEE 1700 has a rectangular shape. The shape and aspect ratioare not critical to the present invention, however, and LEE 1700 mayhave any desired shape. In various embodiments, the extent of one orboth of contacts 1760, 1770 in one dimension (e.g., a diameter or sidelength) is less than approximately 100 μm, less than approximately 70μm, less than approximately 35 μm, or even less than approximately 20μm. In one embodiment, contacts 1760, 1770 are rectangular and may havea length in the range of about 10 μm to about 250 μm and a width in therange of about 5 μm to about 50 μm. In other embodiments, contacts 1760,1770 have any shape or size, and in some embodiments LEE 1700 has morethan two contacts. The number, shape and aspect ratio of the contactsare not critical to the present invention; however, and contacts 1760,1770 may have any desired number, shape and/or size. In someembodiments, contacts 1760 and 1770 are separated as far as possiblewithin the geometry of LEE 1700. For example, in one embodiment theseparation between contacts 1760 and 1770 is in the range of about 75%to over 90% of the length of LEE 1700, however the separation betweencontacts is not a limitation of the present invention.

In some embodiments where electrical contact to contacts 1760, 1770 isfacilitated via use of a conductive adhesive rather than, e.g., wirebonding, soldering, ultrasonic bonding, thermosonic bonding or the like,contacts 1760, 1770 may have a relatively small geometric extent sinceadhesives may be utilized to contact even very small areas impossible toconnect with wires or ball bonds (which typically require bond areas ofabout 80 μm on a side). The method of die attach is not a limitation ofthe present invention and in other embodiments any die-attach method,for example solder, wire bonding, solder bump, stud bump, thermosonicbonding, ultrasonic bonding or the like may be used. In some embodimentsone or more contacts, for example contacts 1760 and/or 1770 may includestud bumps or solder bumps.

Particularly if LEE 1700 includes or consists essentially of alight-emitting device such as a LED or laser, contacts 1760, 1770 may bereflective to a wavelength of light emitted by LEE 1700) and hencereflect emitted light back toward substrate 1710. In some embodiments, areflective contact 1760 covers a portion or substantially all of layer1740, while a reflective contact 1770 covers a portion or substantiallyall of layer 1720. In addition to or instead of reflective contacts, areflector (not shown in this figure for clarity) may be disposed betweenor above portions of contacts 1760, 1770 and over portions orsubstantially all of layer 1740 and 1720. The reflector is reflective toat least some or all wavelengths of light emitted by LEE 1700 and mayinclude or consist essentially of various materials. In one embodiment,the reflector is non-conductive so as not to electrically connectcontacts 1760, 1770. The reflector may be a Bragg reflector. Thereflector may include or consist essentially of one or more conductivematerials, e.g., metals such as silver, gold, platinum, etc. Instead ofor in addition to the reflector, exposed surfaces of semiconductor dieexcept for contacts 1760, 1770 may be coated with one or more layers ofan insulating material, e.g., a nitride such as silicon nitride or anoxide such as silicon dioxide. In some embodiments, contacts 1760, 1770include or consist essentially of a bond portion for connection to acircuit board or power supply or the like and a current-spreadingportion for providing more uniform current through LEE 1700, and in someembodiments, one or more layers of an insulating material are formedover all or portions of LEE 1700 except for the bond portions ofcontacts 1760, 1770. Insulating material 1750 may include or consistessentially of, for example, polyimide, silicon nitride, silicon oxideand/or silicon dioxide. Such insulating material 1750 may cover all orportions of the top and sides of LEE 1700 as well as all or portions ofthe top and sides of layers 1720, 1730 and 1740. Insulating material1750 may act to prevent shorting between contacts 1760 and 1770 andbetween conductors to which contacts 1760 and 1770 may be electricallycoupled.

FIG. 18 shows one embodiment of white die 200 comprising an LEE 1700 asdescribed above. White die 200 as shown in FIG. 18 may be manufacturedin accordance with any of various embodiments of the present invention.As shown in FIG. 18, LEE 1700 includes an optional reflective layer1810.

Advantageously, embodiments of the present invention produce white dies200 having controlled binder thickness, uniformity and distribution ofphosphor particles in the binder around LEE 210, for example a uniformor substantially uniform thickness and uniform or substantially uniformdistribution of phosphor particles in the binder, or an engineeredthickness and distribution of phosphor particles to achieve uniform orotherwise specified optical characteristics. The thickness anddistribution, or loading, of the phosphor particles may have a strongimpact on the uniformity of the color temperature of the light. Insystems with a plurality of LEEs, and in particular arrays with tens tothousands of LEEs, it may be difficult to achieve such phosphor coatingover all of the LEEs when utilizing conventional phosphor-integrationtechniques, resulting in non-uniform optical characteristics. FIG. 19 isa schematic of the CIE chromaticity diagram with the blackbody locus1910 and an ellipse 1920 representing one or more MacAdam ellipses. Themajor axis of MacAdam ellipse 1920 is labeled as 1940 while the minoraxis is labeled as 1930. A MacAdam ellipse represents a region of colorson the chromaticity chart and a one-step MacAdam ellipse represents therange of colors around the center of the ellipse that areindistinguishable to the average human eye, from the color at the centerof the ellipse. The contour of a one-step MacAdam ellipse thereforerepresents barely noticeable differences of chromaticity.

Multiple-step MacAdam ellipses may be constructed that encompass largerranges of color around the center point. The black body locus is ingeneral aligned with the major axis of a MacAdam ellipse, meaning thatthe eye is less sensitive to color differences along the black bodyline, which equates to red/blue shifts, than to differencesperpendicular to the black body line, which equates to a green/magentashift. Furthermore, with respect to phosphor-converted white lightsources, the variation in the minor axis direction 1930 is in largemeasure determined by the LEE (typically a LED) wavelength variation,while the variation in the major axis direction 1940 may be largelydetermined by the phosphor concentration and thickness. While there aremany recommendations as to how tight the color temperature uniformityshould be (as measured by MacAdam ellipses or other units), it is clearthat a variation encompassed within a smaller step number of MacAdamellipses (smaller ellipse) is more uniform than one encompassed within alarger step number of MacAdam ellipses (larger ellipse). For example, afour-step MacAdam ellipse encompasses about a 300K color temperaturevariation along the black body locus, centered at 3200K, while atwo-step MacAdam ellipse encompasses about a 150K color temperaturevariation along the black body locus, centered at 3200K.

The importance of uniform and/or controlled or engineered thickness andphosphor concentration in white die 200 may be seen in relation to theMacAdam ellipse on the chromaticity chart of FIG. 19. Since the majoraxis length is largely determined by the phosphor concentration andthickness, variations in these parameters result in an increase in themajor axis of the MacAdam ellipse and thus an increase in the variationin color temperature. The aforementioned method for fabrication ofuniform thickness and composition phosphor as part of white die 200results in a reduction in the variation in color temperature and thus amore uniform color temperature light source, both within a lightingsystem featuring an array of phosphor-converted LEEs, as well as betweensuch lighting systems. The use of the aforementioned LEEs in lightingsystems featuring large arrays of LEE permits the manufacture of largenumbers of lighting systems having uniform color temperatures. In someembodiments, white dies 200 are manufactured that have a distribution ofcolor temperature less than 500K, or less than 250K or less than 125K orless than 75K. In some embodiments, white dies 200 are manufactured thathave a variation in color temperature or chromaticity of less than fourMacAdam ellipses, or less than two MacAdam ellipses, or less than oneMacAdam ellipse. In some embodiments, such tight distributions areachieved within one white wafer, or within a batch of white wafers orwithin the entire manufacturing distribution.

One step in the method of manufacture of some embodiments of the presentinvention is to dispense, cast, pour or otherwise form a phosphor overLEE on a base. In one embodiment of the present invention, the amount ofphosphor formed is controlled manually by controlling the dispensingprocess. For example, the phosphor may be poured over the LEE and thebase. However, this approach may not provide the desired level ofcontrol of the amount of phosphor formed. Various methods may be used toimprove the control and accuracy of the formation process. For example,in one embodiment a mold or barrier walls are formed around the LEE.This results in a volume defined by the area of the mold and the desiredphosphor height. The phosphor may be dispensed by volume, for examplefrom a calibrated syringe, pipette or other volumetric dispensingsystem, to provide the desired volume of phosphor in the mold area. Inanother example, the mold may be on a scale and the phosphor may bedispensed until a certain weight of phosphor has been formed. The moldvolume along with the phosphor density may be used to calculate therequired weight of phosphor to achieve the desired phosphor amount orcoverage.

In another embodiment, the mold height is adjusted to match the desiredamount of phosphor to be formed, and the phosphor-formation process maybe stopped when the phosphor reaches the top of the mold or a certainheight of the sidewall of the mold. Such a process may be performedmanually or automatically. For example, automatic control may beaccomplished using a camera that views the edge of the mold andmodulates and/or stops the phosphor-filling process when the phosphorreaches a certain height relative to the mold wall or top surface of themold.

In one embodiment, the thickness of the phosphor is controlled byfeedback during the filling or dispensing process. In one embodiment,the phosphor is excited by an appropriate pump source, for example a LEEsuch as a LED or laser and the resulting white light color temperaturemeasured (i.e., from the emission from the phosphor or phosphor andLEE). When the target white light color temperature is reached, the fillmechanism is notified to stop the filling or dispensing process. FIG. 20shows an example of such an embodiment, featuring base or mold 410, areservoir 2040 of phosphor 420, phosphor 420 also in mold 410, valve2030, a pump source 2010 and a detector 2020. The target colortemperature is compared to that measured by detector 2020, and when thetarget color temperature is reached, detector 2020 sends a signal toclose valve 2030, stopping further dispensing of phosphor 420 into mold410. In some embodiments, detector 2020 and valve 2030 control in anon-off configuration while in other embodiments a proportional control,for example a metering valve, is used. In some embodiments, an offset inthe timing or valve-control signal is included to accommodate hysteresisor delays in the mold-filling process. Mold 410 may be transparent orhave a transparent region or window to a wavelength of light emitted bypump source 2010. In one embodiment, phosphor 420 is excited from thetop rather than through mold 410. In one embodiment, pump source 2010has a spectral power distribution the same as, substantially the same asor similar to that of LEE 210. In one embodiment, pump source 2010includes or consists essentially of one or more LEE 210. In oneembodiment, mold 410 consists essentially of base 410. In oneembodiment, mold 410 includes or consists essentially of base 410 andsidewalls or barriers 450, as shown in FIG. 4. In one embodiment,reservoir 2040 and valve 2030 are replaced by a pressure-assisteddispense system. FIG. 20 shows one pump source 2010, one detector 2020and one reservoir 2040 with valve 2030; however, this is not alimitation of the present invention, and in other embodiments aplurality of any one or more of these features may be utilized. Themethod of dispense and/or control is not a limitation of the presentinvention. FIG. 20 shows one configuration of such a filling controlscheme; however, other configurations may be employed, and the specificconfiguration is not a limitation of the present invention.

In one embodiment, one or more LEEs 210 are themselves energized toprovide the source of pump radiation. After phosphor 420 is deposited ordispensed, it may be cured and the resulting structure processed asdescribed in accordance with any of various embodiments describedherein. In some embodiments, a combination of formation techniques isused. For example, in one embodiment a portion of phosphor 420 is formedor dispensed in a manual fashion or without feedback. This first portionmay be cured or partially cured. Then, a second portion of phosphor 420is dispensed or formed under feedback control.

In some embodiments, it is desirable to keep phosphor 420 level toensure a uniform layer of phosphor 420 over LEE 210. In one embodiment,this is done by providing a mechanically level surface on which base ormold 410 or the like is positioned. In one embodiment, the level surfaceis formed within an oven that is used for curing or partially curingphosphor 420. In one embodiment, base or mold 410 or the like is floatedupon a liquid in a larger container. FIG. 21 shows an example of thisembodiment featuring a container 2100, mold 410, phosphor 420, LEE 210and a liquid 2120. Even if container 2100 is not level, the surface 2110of liquid 2120 will be level due to gravity, resulting in floating mold410 being level. This will then result in phosphor 420 in mold 410 beinglevel. In one embodiment, phosphor 420 is activated to aid in theleveling process. Such activation may include shaking, vibrating,rocking, agitation, ultrasonificiation or the like.

In one embodiment, an active feedback leveling system is used to ensurethat base or mold 410 or the like is level. Such a system, in oneexample, includes one or more level sensors 2210, an optional controller2220 and one or more actuators 2230 acting to level base or mold 410 ora support on which base or mold 410 is placed, as shown in FIG. 22.Level sensor 2210 senses the orientation of base or mold 410 and sends asignal to controller 2220. Controller 2220 utilizes the signal from theone or more level sensors 2210 to determine and send appropriateactuation signals to actuators 2230 to make base or mold 410 level orsubstantially level. Level sensor 2210 may be, for example, a physicallevel sensor or a solid-state or micromachined level sensor or the like.Actuator 2230 may include or consist essentially of a piezoelectrictranslator, a mechanical translator, an electromechanical translator orthe like. The type of level sensor and/or actuator and/or controller isnot a limitation of the present invention.

In some embodiments, the physical layout of white dies 200 discussedherein makes them amenable to transfer or pick-and-place operations ofmultiple units at a time. As discussed above, some embodiments of thepresent invention result in regular periodic arrays of white dies 200 ona base, for example base 410, from which a multiple-tool pick-and-placeor stamp operation may be fed with almost 100% utilization of all whitedies 200 in the array, where the pick or stamp pitch is an integermultiple of the pitch of white dies 200 in the source array.

FIGS. 23-25 show additional embodiments of the present invention relatedto processing and/or removal or partial removal of the substrateassociated with LEE 210. As shown in FIG. 17A, LEE 1700 may include asubstrate 1710. As discussed above, substrate 1710 may include orconsist essentially of sapphire, silicon carbide, silicon, GaAs, or thelike.

In some embodiments it may be advantageous to remove all or a portion ofsubstrate 1710 from LEE 1700. In some examples substrate 1710 isabsorbing or partially absorbing to a wavelength of light emitted by LEE1700 (for example where substrate 1710 includes silicon, siliconcarbide, or GaAs) and removing or partially removing substrate 1710 mayresult in a larger amount of light being emitted from LEE 1700 becauseof decreased or no absorption in substrate 1710. In one embodiment LEE1700 may include a III-nitride based light emitter grown on a siliconsubstrate. Even in examples where substrate 1710 is transparent orpartially transparent to a wavelength of light emitted by LEE 1700 (forexample where substrate 1710 includes sapphire or silicon carbide),removal of substrate 1710 may be advantageous. For example, removal orpartial removal of substrate 1710 may result in a reduction orelimination of scattering and absorption in substrate 1710, with theresult that the light from LEE 1700 is substantially emitted from aplane, rather than a volume (where the volume emission is mainly fromsubstrate 1710). This may also permit a smaller white die 200 becausethe size of phosphor 230 may be reduced around the periphery of LEE1700, as shown in FIGS. 23A and 23B.

Substrate 1710 may be removed using a variety of techniques, for exampleincluding lapping, grinding, polishing, exfoliation, ablation, wetchemical etching, dry etching, for example reactive ion etching, laserlift off, radiation-enhanced lift-off or the like. The method of removalof substrate 1710 is not a limitation of the present invention. In oneembodiment, substrate 1710 includes or consists essentially of sapphireand layer 1720 includes or consists essentially of GaN, and substrate1710 is removed using laser lift-off or other techniques. In oneembodiment, substrate 1710 includes or consists essentially of siliconand layer 1720 includes or consists essentially of GaN, and substrate1710 is removed using one or more of exfoliation, grinding, lapping,polishing, wet chemical etching or dry chemical etching or othertechniques. In one example the process of substrate removal may beinserted between the steps associated with FIGS. 4A and 4B. FIG. 24Ashows the structure of FIG. 4A, but identifying substrate 1710 anddevice 2410 as part of LEE 210 or LEE 1700 (in one embodiment, withrespect to FIG. 17A, device 2410 comprises LEE 1700 less substrate1710). FIG. 24B shows the structure of FIG. 24A at a later stage ofmanufacture, but before the step shown in FIG. 4B. FIG. 24B shows thestructure of FIG. 24A after removal of substrate 1710, for example byusing laser lift-off. Other embodiments may include only partial removalof substrate 1710. FIG. 24C shows the structure of FIG. 24B at a laterstage of manufacture, corresponding to the step shown in FIG. 4B, afterphosphor 420 has been formed over device 2410 and base 410. At thispoint the process may continue as discussed above in reference to FIGS.4B-4E. In some embodiments, a plurality of steps are used to removesubstrate 1710. For example, a portion of substrate 1710 may be removedby grinding and/or lapping prior to singulation of LEE 210 and mountingon base 410. The remaining portion of substrate 1710 may then be removedusing wet or dry chemical etching. In some embodiments substrate removalmay include only removal of a portion of the substrate, while in otherembodiments substrate removal includes removal of all or substantiallyall of the substrate.

In some embodiments, light is internally reflected within substrate 1710and/or layer 1720, in particular in layer 1720 if substrate 1710 hasbeen removed. Such reflection is called total internal reflection (TIR)and may reduce the amount of light exiting LEE. TIR typically occursbecause of the index of refraction differences between adjacent layersand/or substrate or between the external layer or substrate and theadjacent material, for example binder, phosphor, air or the like.

Various approaches may be used to reduce TIR and provide increased lightextraction from substrate 1710 and/or layer 1720, for example bypatterning or roughening the external surface of these layers orpatterning or roughening the interface between substrate 1710 and layer1720 or forming an layer over the outside surface having an index ofrefraction between those of the two adjacent materials. In oneembodiment, substrate 1710 is patterned before formation of layer 1720.In the case where substrate 1710 includes sapphire, this may be calledpatterned sapphire substrate (PSS). PSS may be formed using etching or acombination of patterning and etching. Etching may be done by wetchemical etching, dry etching, for example RIE, ablation or the like.The method of formation of the PSS is not a limitation of the presentinvention. FIG. 25 shows an embodiment of a white die 200 featuring aPSS 2510. Patterning of substrate 1710 before formation of layer 1720typically results in the formation of a minor image of the pattern inthe adjacent surface of layer 1720.

PSS may also be used in combination with laser lift-off to form astructure similar to that shown in FIG. 23A or FIG. 23B, but with apatterned external surface of layer 1720, as shown in FIG. 26. Asdiscussed above, growth of layer 1720 on PSS 1710 typically forms theminor-image pattern in the adjacent surface of layer 1720. Laserlift-off may then be used to remove PSS 1710, leaving a patternedsurface 2610. Such a process may be carried out using the approachdescribed in reference to FIG. 24A-24C, where LEE 210 in FIG. 24Acomprises a substrate 1710 featuring PSS, as described above. Substrate1710 is then removed, as shown in FIG. 24B, and phosphor 230 formed, asdescribed above, resulting in the white die structure shown in FIG. 26.

Patterning or roughening of the external surface of LEE 210 adjacent tophosphor 230 may be accomplished by other techniques, and may be appliedto LEE 210 both with and without substrate 1710. In one embodiment, theoutside surface of substrate 1710 is patterned or roughened beforeformation of phosphor 230. Such patterning or roughening may be done atvarious points in the process, for example when LEEs 210 are in waferform or after singulation. Such patterning or roughening may also beapplied to the layer adjacent to phosphor 230 in the case wheresubstrate 1710 has been removed, for example layer 1720 in FIGS. 23A and23B. Such patterning or roughening may be done by using for exampleablation, wet chemical etching, dry etching, for example reactive ionetching, laser etching or the like, either alone or in combination or incombination with patterning. As discussed above, the external surface ofphosphor 230 may also be patterned or roughened to reduce TIR withinphosphor 230. Such patterning or roughening may be done during theformation process of phosphor 230, as described above, or afterformation of phosphor 230, for example ablation, wet chemical etching,dry etching, for example reactive ion etching, molding, imprinting,indentation, cutting, laser etching or the like, either alone or incombination or in combination with patterning. In some embodiments suchpatterning and/or roughening may be applied to portions of LEE 210 otherthan the substrate side, for example to all or portions of the sidewallsand/or top.

In yet another embodiment, substrate 1710 may include a plurality oflayers or materials, for example silicon on sapphire, silicon on aceramic material such as SiC or AlN, GaN on sapphire, GaN on a ceramicmaterial such as SiC or AlN or the like. In this case, one or more ofthe above processes may be applied to a multilayer substrate 1710, forexample to remove one or more portions or layers of substrate 1710, orto increase light extraction by reducing TIR.

Embodiments of the present invention permit the manufacture of verylarge arrays of white dies 200 in an economical manner with relativelynarrow output characteristics. In some embodiments, the spacing betweenLEEs 210 in the array is determined by the desired amount of phosphor onthe sides of LEEs 210 and the kerf of the method used for separatingwhite dies 200. In some embodiments, the amount of phosphor on the sidesof LEEs 210 may range from about 10 μm to about 1000 μm, while the kerfmay range from about 2 μm to about 200 μm. The size of LEEs 210 mayrange from about 10 μm to about 2000 μm or more. The size of LEEs 210,the width of phosphor on the sides of LEEs 210 and the kerf width arenot limitations of the present invention. As an example, in oneembodiment an LEE 210 has a size of about 375 μm on a side, the phosphorthickness on the sides of LEE 210 is about 100 μm and the kerf is about25 μm, resulting in a space between LEEs 210 of about 225 μm. Thisresults in a white die size of about 575 μm and a pitch of about 600 μm.This leads to a density of white dies of about 2.77/mm² or about 275white die per square cm. The manufacturing approaches described abovemay be practiced on any arbitrary size area. In one embodiment, the areais about 10 cm×about 10 cm, or about 1000 cm². In this example, thisleads to the ability to manufacture 275,000 white dies 2610simultaneously. This is just one example and not meant to be limiting tothe invention. In general the density of white dies 200 will vary withthe size of LEEs 210, the kerf and the amount of phosphor required onthe sides of LEEs 210. In another example white dies 200 may have a sizeof 975 μm, and a pitch of about 1000 μm or about 1 mm, resulting in adensity of about 100 white dies 200 per square cm and the ability tomanufacture about 100,000 white dies 200 simultaneously in an area ofabout 10 cm×about 10 cm. In some embodiments white dies 200 may eachcomprise a plurality of LEEs 210, for example a 5×5 or 10×10 or 10×20array associated with one phosphor 230. The number of LEEs or size ofthe white dies are not limitations to the present invention.

As will be appreciated by those with ordinary skill in the art, whitedies 210 may be made using a wide range of processes, while still withinthe bounds of the present invention. For example, the table below showsa non-exclusive list of process steps that may be selected from and usedin various orders to manufacture white dies 200.

Test LEEs Sort and bin LEEs Virtual sort and bin LEEs (generate wafermaps) Singulate LEEs Transfer LEE wafer Transfer singulated LEEs Preparephosphor Form phosphor over LEEs Cure phosphor Form optic over white dieTest white wafer Singulate white wafer Sort and bin white dies Sort andbin white wafers Virtual sort and bin white wafers Test white dies

FIG. 27 shows one embodiment of a lighting system or portion of alighting system 2700 featuring white dies 200. Lighting system 2700includes an LEE substrate 2720 over which conductive traces 2730 havebeen formed. White dies 200 are then formed or placed over conductivetraces 2730 such that contacts 220 on LEE 210 are electrically coupledwith conductive traces 2730. In the example in FIG. 27, white dies 200are electrically coupled to conductive traces 2730 using material 2740,which may include or consist essentially of a conductive adhesive, ananisotropic conductive adhesive (as disclosed in U.S. patent applicationSer. No. 13/171,973, filed Jun. 29, 2011, the entire disclosure of whichis incorporated by reference herein), a combination of conductive andnon-conductive adhesives, conductive epoxy or the like. In oneembodiment, the adhesive is reflective to a wavelength of light emittedby either or both of LEE 210 and phosphor 230. However, the method ofelectrical coupling and attachment of LEE 210 or white die 200 toconductive traces 2730 is not a limitation of the present invention andin other embodiments other methods of electrical coupling and attachmentmay be used.

LEE substrate 2720 may include or consist essentially of asemicrystalline or amorphous material, e.g., polyethylene naphthalate(PEN), polyethylene terephthalate (PET), acrylic, polycarbonate,polyethersulfone, polyester, polyimide, polyethylene, and/or paper. LEEsubstrate 2720 may also include or consist essentially of a rigid orflexible circuit board, for example FR4, metal core printed circuitboard (MCPCB), polyimide or the like. LEE substrate 2720 may besubstantially flexible, substantially rigid or substantially yielding.In some embodiments, the substrate is “flexible” in the sense of beingpliant in response to a force and resilient, i.e., tending toelastically resume an original configuration upon removal of the force.A substrate may be “deformable” in the sense of conformally yielding toa force, but the deformation may or may not be permanent; that is, thesubstrate may not be resilient. Flexible materials used herein may ormay not be deformable (i.e., they may elastically respond by, forexample, bending without undergoing structural distortion), anddeformable substrates may or may not be flexible (i.e., they may undergopermanent structural distortion in response to a force). The term“yielding” is herein used to connote a material that is flexible ordeformable or both.

LEE substrate 2720 may include multiple layers, e.g., a deformable layerover a rigid layer, for example, a semicrystalline or amorphousmaterial, e.g., PEN, PET, polycarbonate, polyethersulfone, polyester,polyimide, polyethylene, paint, plastic film and/or paper formed over arigid or substantially rigid substrate for example including, ceramicsuch as AlN, fiberglass, such as FR-4, metal core printed circuit board,acrylic, aluminum, steel and the like. In some embodiments, LEEsubstrate 2720 is rigid or substantially rigid, for example includingceramic such as AlN, fiberglass, such as FR-4, metal core printedcircuit board, acrylic, aluminum, steel and the like.

Depending upon the desired application for which embodiments of theinvention are utilized, LEE substrate 2720 is substantially opticallytransparent, translucent, or opaque. For example, LEE substrate 2720 mayexhibit a transmittance or a reflectivity greater than about 80% foroptical wavelengths ranging between approximately 400 nm andapproximately 700 nm. In some embodiments, LEE substrate 2720 exhibits atransmittance or a reflectivity of greater than about 80% for one ormore wavelengths emitted by LEE 210 and/or white die 200. LEE substrate2720 may also be substantially insulating, and may have an electricalresistivity greater than approximately 100 ohm-cm, greater thanapproximately 1×10⁶ ohm-cm, or even greater than approximately 1×10¹⁰ohm-cm.

Conductive traces 2730 may include or consist essentially of anyconductive material, for example metals such as gold, silver, aluminum,copper, carbon and the like, conductive oxides, carbon, etc. Conductivetraces 2730 may be formed on LEE substrate 2720 by a variety oftechniques, for example evaporation, sputtering, physical deposition,chemical vapor deposition, plating, electroplating, printing,lamination, gluing using an adhesive, lamination and patterning or thelike. In one embodiment, conductive traces 2730 are formed usingprinting, for example screen printing, stencil printing, flexo, gravure,ink jet, or the like. Conductive traces 2730 may include or consistessentially of silver, aluminum, copper, gold, carbon inks, or otherconductive inks or the like. Conductive traces 2730 may include orconsist essentially of a transparent conductor, for example, atransparent conductive oxide such as indium tin oxide (ITO). Conductivetraces 2730 may include or consist essentially of a plurality ofmaterials. Conductive traces 2730 may optionally feature stud bumps toaid in electrical coupling of conductive trace 2730 to contacts 220.Conductive traces 2730 may have a thickness in the range of about 0.05μm to about 100 μm; however, this is not a limitation of the presentinvention, and in other embodiments conductive traces 2730 may have anythickness. While the thickness of one or more of the conductive traces2730 may vary, the thickness is generally substantially uniform alongthe length of the conductive trace 2730 to simplify processing. However,this is not a limitation of the present invention and in otherembodiments the conductive trace thickness or material varies.

In one embodiment, one or more white dies 200 are electrically coupledto conductive traces 2730 using a conductive adhesive, e.g., anisotropically conductive adhesive and/or an anisotropically conductiveadhesive (ACA). An ACA is a material that permits electrical conductiononly in the vertical direction but insulates the conductive trace 2730from each other. As used here, ACA may be an anisotropic conductivematerial in any form, for example paste, gel, liquid, film or otherwise.ACAs may be utilized with or without stud bumps.

The systems described above may be combined with additional electronicsto form an electronic device 2800 as shown in FIG. 28. In oneembodiment, the device includes a plurality of white dies 200 that areelectrically coupled to traces 2730. As shown, electronic device 2800includes three serially-connected strings 2810 of white dies 200.Electronic device 2800 also includes circuitry 2820 electricallyconnected to one or more of strings 2810. Circuitry 2820 may include orconsist essentially of portions or substantially all of the drivecircuitry, sensors, control circuitry, dimming circuitry, and orpower-supply circuitry or the like, and may also be adhered (e.g., viaan adhesive) or otherwise attached to substrate 2720. In one embodiment,the power supply and driver are distributed, e.g., the device 2800 mayhave a centralized power supply and all or a portion of the drivecircuitry distributed in different locations. Circuitry 2820 may even bedisposed on a circuit board (e.g., a printed circuit board) that itselfmay be mechanically and/or electrically attached to substrate 2730. Inother embodiments, circuitry 2820 is separate from substrate 2730. Insome embodiments circuitry 2820 is formed on substrate 2730. While FIG.28 depicts white dies 200 electrically coupled in serially connected instrings 2810, and strings 2810 connected or connectable in parallel,other die-interconnection schemes are possible and within the scope ofembodiments of the invention.

As shown in FIG. 28, the lighting system 2800 may feature multiplestrings, each string 2810 including or consisting essentially of acombination of one or more white dies 200 electrically connected inseries, in parallel, or in a series-parallel combination with optionalfuses, antifuses, current-limiting resistors, zener diodes, transistors,and other electronic components to protect white die 200 from electricalfault conditions and limit or control the current flow throughindividual white dies 200. In general, such combinations feature anelectrical string that has at least two electrical connections for theapplication of DC or AC power. A string may also include a combinationof one or more white dies 200 electrically connected in series, inparallel, or in a series-parallel combination of white dies 200 withoutadditional electronic components. FIG. 28 shows three strings of whitedies 200, each string having three white dies 200 in series; however,this is not a limitation of the present invention, and in otherembodiments the number of strings is less than or greater than three andthe number of white dies 200 in a string is greater or less than three.In one embodiment, a string includes at least ten white dies 200. In oneembodiment, a string includes at least 45 white dies 200. In oneembodiment, system 2800 includes at least ten strings. In oneembodiment, system 2800 includes at least 50 strings.

In some embodiments, variations in optical characteristics of LEEs 210are accommodated during the fabrication of white dies 200. In oneembodiment, where the variation in the optical characteristic, forexample wavelength, is relatively monotonic or known or predictableacross the physical layout of LEEs 210, mold 3110 may be tilted orterraced or sloped to provide a variation in thickness of phosphor 420over LEE 210, as shown generically in FIG. 29 before curing of phosphor420. A feedback system similar to that shown in FIG. 20 may be used todetermine the optimum tilt value. In another embodiment, the tilt isdetermined from a map of the characteristics of the array of LEEs 210.In another embodiment, the tilt is introduced manually. In anotherembodiment, the bottom surface is terraced, for example by conforming itto a terraced chuck, e.g., a terraced vacuum chuck. In FIG. 29, LEE 210′receives a thicker phosphor layer thereover than does LEE 210″. Afterthe proper tilt is achieved, phosphor 420 is cured and the resultingstructure may be processed as described elsewhere in this description.The example shown in FIG. 29 shows a tilted mold 410, however in otherembodiments mold 410 is terraced.

In one embodiment of this aspect of the invention, the spacing betweenLEEs 210, and thus the amount of phosphor 230 surrounding the sides ofan LEE 210, is substantially constant. In one embodiment, the spacingbetween LEEs 210, and thus the amount of phosphor 230 surrounding thesides of LEEs 210, is chosen to be the maximum required for the array ofLEEs 210 under fabrication. In one embodiment, the cutting or separationprocess produces phosphor 230 of different sizes, in relation to afeedback system or a prior input, for example a map of one or moreoptical characteristics. For example a laser-based cutting system may bedirected to cut different size phosphors 230 around different LEEs 210,based on some form of input, for example, feedback, a map, etc.

FIG. 30 shows another embodiment of a system to optimize the phosphorand LEE combination. LEEs 210 may be placed on a film or base 3010. Abarrier 3015 is optionally present to contain phosphor 420. LEEs 210 areenergized to provide a signal to a detector 3030. The signal is thensent to a controller 3040 that controls a series of actuator pins 3020on an actuator base 3025. If more phosphor is desired above a particularLEE 210, the associated actuator pin 3020 may move down or remain inplace. For LEEs 210 that require less phosphor above them, theassociated actuator pin 3020 may move up or remain in place. In oneembodiment, all LEEs 210 are actuated simultaneously and detector 3030simultaneously detects the light from each LEE 210 and its surroundingphosphor 420. In one embodiment, each LEE 210 is energized separately.Thus, detector 3030 may be a fixed or moveable detector, or a stage uponwhich actuator base 3010 is positioned may be moved relative to detector3030. After all actuator pins 3020 are in their correct position,phosphor 420 may be cured and the resulting structure processed asdescribed elsewhere in this description. In one embodiment actuator pins3020 are controlled in response to a map of the characteristics of LEEs210.

Structures such as those discussed in relation to FIG. 12 or thatutilize shaped or textured phosphor may also be manufactured by anadditive or subtractive process, carried out during or after theformation of white dies 200. For example, in some embodiments a whitedie 200 having any shape is subsequently shaped by addition of morephosphor either uniformly or selectively over portions of white die 200.In some embodiments, a white die 200 having any shape is subsequentlyshaped by removal of one or more portions of phosphor either uniformlyor selectively over portions of white die 200.

In some embodiments of the present invention it may be desirable tofacilitate removal of the white dies or white die wafer from moldsubstrate 410. For example in some cases the adhesion of phosphor tomold substrate 410 may be relatively high and reduction of the adhesionmay facilitate the manufacturing process. In some embodiments moldsubstrate 410 may be formulated or treated to have difference levels ofadhesion to facilitate various aspects of the process. For example, moldsubstrate 410 may have regions of relatively higher adhesion under LEEs210 and regions of relatively lower adhesion in the areas between LEEs210. In some embodiments this may facilitate adhesion of LEEs 210 tomold substrate 410 during the initial steps in the process, while alsofacilitating removal of the white dies or white die wafer from moldsubstrate 410 after the phosphor is cured or partially cured. FIGS.31A-31C show one embodiment of such an approach, starting with FIG. 31A,in which LEEs 210 are formed over mold substrate 410. FIG. 31B shows thestructure of FIG. 31A at a later stage of manufacture, in which thestructure is treated using treatment 3100 to reduce the adhesion levelof mold substrate 410 in general or to phosphor 230 in particular. FIG.31C shows the structure of FIG. 31B after treatment 3100, with regions3110 having relatively reduced adhesion after treatment 3100. In someembodiments, treatment 3100 may be a plasma treatment, a wet chemicaltreatment, exposure to radiation or the like. In some embodimentstreatment 3100 may include formation of a material, for example a moldrelease compound on mold substrate 410, to facilitate removal of thewhite dies or white die wafer after the phosphor is cured. In someexamples of this embodiment, the material that was formed on the top ofLEEs 210 during treatment 310 (if any) may be left in place, while inothers the material formed on the top of LEEs 210 may be removed beforeformation of phosphor 230. The specific treatment 3100 is not alimitation of the present invention.

FIGS. 31A-31C show one embodiment using LEEs 210 as the mask fortreatment 3100; however, this is not a limitation of the presentinvention, and in other embodiments other approaches may be used. Forexample a stencil or mask may be applied to or over mold substrate 410to provide the pattern for application of treatment 3100. In oneembodiment treatment 3100 is applied selectively, without the need for astencil or mask. For example treatment 3100 may be applied by anapplicator on an x-y stage that is moved over mold substrate 410, ormold substrate 410 may be moved under a fixed applicator. In oneembodiment the adhesion may be reduced by removal of all or a portion ofthe adhesive layer or component on mold substrate 410. In differentembodiments this may be done by spraying, dispensing, scraping or thelike.

In another embodiment a film may be selectively applied to moldsubstrate 410 that has reduced adhesion to cured phosphor 230. FIGS. 32Aand 32B show one embodiment of such an approach. FIG. 32A shows LEEs 210on mold substrate 410. A film 3210, for example a mold release film, hasbeen selectively applied to this structure. Application may be donebefore or after provision of LEEs 210 on mold substrate 410. In someembodiments film 3210 includes a cut-out or hole which leaves an openarea for positioning of LEEs 210 directly on mold substrate 410 while inother cases the cut-out permits overlaying film 3210 on mold substrate410 after LEEs 210 are formed on mold substrate 410. FIG. 32B shows thestructure of FIG. 32A after application and curing of phosphor 320. Asmay be seen, this structure may facilitate the removal of white dies(after singulation) or the white die wafer because the regions includingfilm 3210 have reduced adhesion to phosphor 230.

In one embodiment film 3210 may be used as a method to control dieand/or contact relief, as shown schematically in FIGS. 33A and 33B. FIG.33A shows a close-up view of one die from FIG. 32B showing the thicknessof film 3210 relative to the edge of LEE 210. The thickness of film 3210may be adjusted to achieve a certain die relief 950, as shown in FIG.33B for the white die of FIG. 33A after singulation and removal frommold substrate 410. In one embodiment film 3210 may be spaced apart fromthe edge of LEE 210, as shown in FIG. 33C to produce a white die with astepped die relief 950, as shown in FIG. 33D.

In some embodiments mold substrate 410 may be composed of more than onematerial, where each of the materials is optimized for a specificpurpose. For example FIG. 34 shows mold substrate 410 having portions3410 and 3420. In one embodiment portion 3410 is optimized to have anadhesive level appropriate to hold LEEs 210 in place during the process,while portion 3420 is optimized to have an adhesive level low enough topermit facile removal of cured phosphor 230.

In yet another embodiment mold substrate 410 includes or consistsessentially of a compressible or deformable material, into which all ora portion of the contacts and/or a portion of LEE 210 may be embedded,as shown in FIGS. 35A and 35B. FIG. 35A shows all or portions of thecontacts embedded into mold substrate 410, while FIG. 35B shows thecontacts and a portion of the sidewall of the die embedded into moldsubstrate 410. In some embodiments this may be used as a way to controldie and/or contact relief. In some embodiments the deformable layer maycomprise an adhesive layer on mold substrate 410, while in otherembodiments the deformable layer may not have substantial adhesion toLEEs 210. In one embodiment the mold substrate is patterned orstructured to control the die relief; for example, the mold substratemay have an indentation into which a portion of LEE 210 is inserted, asshown in FIG. 36.

While the discussion above has focused on reduction of adhesion in theregions adjacent to LEEs 210, other approaches may be utilized, forexample to increase the adhesion in the region under LEEs 210. Forexample, mold substrate 410 may have a relatively low adhesion, inparticular to phosphor 230, but then may not have sufficient adhesion tohold LEEs 210 in place during the process. In some embodiments, such amold substrate 410 may be treated to increase the adhesion level in theregion under LEEs 210. For example, in one embodiment an adhesive may beselectively deposited on a “non-stick” mold substrate 410. In someembodiments selective application of an adhesive may be done by screenprinting, stencil printing, selective spraying, application of adhesivetape or the like.

In one embodiment mold substrate 410 includes a plurality of holes towhich are applied a vacuum. LEEs 210 are placed over the holes and heldin place by vacuum applied to the holes as shown in FIG. 37. FIG. 37shows mold substrate 410 with holes 3710 that are connected by way ofconnection 3720 to a source of vacuum or a vacuum pump. LEEs 210 areheld in place by the application of vacuum and then after formation ofthe white dies or white die wafer the vacuum is removed, facilitatingremoval of the white dies or white die wafer. While the schematic ofFIG. 37 shows one vacuum hole 3710 for each LEE 210, this is not alimitation of the present invention, and in other embodiments each LEE210 may be associated with more than one vacuum hole 3710. In someembodiments an optional material may be positioned on mold substrate 410between vacuum holes 3710. The optional material may include a moldrelease compound, mold release film or other material or film thatprevents phosphor 230 from sticking to mold substrate 410.

In some embodiments it may be advantageous to position a secondmaterial, for example a pliable or deformable material, between moldsubstrate 410 and all or a portion of each LEE 210. In one embodimentthe pliable or deformable material may facilitate the vacuum seal to LEE210, improving the adhesion of LEE 210 to mold substrate 410. In oneembodiment the pliable or deformable material facilitates removal of thecured white die or white die wafer from mold substrate 410.

In one embodiment mold substrate 410 combines the vacuum holes and astepped structure, as shown in FIG. 38. FIG. 38 also shows optionalsecond material 3810. In one embodiment the structure of FIG. 38 may beused to control the die and/or contact relief. In some embodimentsvarious elements of the approaches described in relation to the moldsubstrate may be used in combination or in an order different from thatdiscussed herein.

In the structures discussed above LEE 210 is shown as including asubstrate, for example substrate 1710 of FIG. 17A; however, this is nota limitation of the present invention, and in other embodiments thesubstrate may be partially or completely removed. FIGS. 39A and 39B showschematics of two possible embodiments of white die 3900, 3901, whereLEE 3910 has the substrate partially or completely removed. In FIG. 39A,phosphor 230 covers all or substantially all of the top surface but verylittle or none of the sides of LEE 3910, while in FIG. 39B phosphor 230covers all or substantially all of the top surface and at least portionsof the sides of LEE 3910. In some embodiments, removal of the substrateresults in no or very little side emission from LEE 3910, and thus allof the light is emitted from the top surface of LEE 3910. In this case,as shown in FIG. 39A, it may be possible to achieve the desired opticalcharacteristics by covering only all or a portion of the top surface ofLEE 3910 with phosphor 230. In an embodiment where side emission stilloccurs, phosphor may be formed on all or a portion of the sidewall ofLEE 3910, as shown in FIG. 39B.

In some embodiments substrate 1710 may include or consist essentiallyof, e.g., silicon or sapphire or gallium arsenide. In one embodiment thestarting structure comprises a III-nitride based LED on a siliconsubstrate. In one embodiment the starting structure comprises aIII-arsenide/phosphide based LED on a gallium arsenide substrate.

FIGS. 40A-40C show one method for manufacture of structures like thoseshown in FIGS. 39A and 39B. FIG. 40A shows a wafer of LEEs that includessubstrate 1710 and device layers 4010 formed over mold substrate 410. Insome embodiments device layers 4010 may comprise layers 1720, 1730 and1740 from FIG. 17A. In FIG. 40A, LEE 3910 is identified by an encirclingdashed line and in some embodiments comprises all of structure 1700 fromFIG. 17A with the exception of all or a part of substrate 1710. FIG. 40Bshows the structure of FIG. 40A at a later stage of manufacture, aftersubstrate 1710 has been removed. In other embodiments the structure ofFIG. 40B may include a portion of substrate 1710. FIG. 40C shows thestructure of FIG. 40B at a later stage of manufacture, after formationand curing of phosphor 230 and singulation into white die 3900.

Substrate 1710 may be removed by a variety of means, for example usingchemical etching, dry etching, reactive ion etching, laser lift-off,lapping, polishing, exfoliation or the like—the method of removal ofsubstrate 1710 is not a limitation of the present invention. In someembodiments a combination of methods may be used to remove substrate1710. In some embodiments a selective removal process, for example aselective etch, or an etch stop layer, may be used to facilitate removalof substrate 1710.

FIG. 40D shows a portion of one embodiment of a method to make white die3901 of FIG. 39B. In this embodiment, all or a portion of layers 4010are removed between adjacent LEEs. In some embodiments a portion ofsubstrate 1710 may also be removed. In this embodiment removal occursbefore formation over mold substrate 410. As may be seen, aftersubstrate 1710 is completely or partially removed, phosphor 230 isformed and cured and singulated, the resulting structure is that ofwhite die 3901, as shown in FIG. 39B. In another embodiment thesubstrate 1710 with the LEEs 210 thereon is singulated before transferto mold substrate 410 (similar to the structure shown in FIG. 4A) andthen substrate 1710 is completely or partially removed while the LEEsare on the mold substrate 410. The method and order of removingsubstrate 1710 relative to formation of phosphor 230 is not a limitationof the present invention.

While the structures shown in FIGS. 39A and 39B each include one LEE3910, this is not a limitation of the present invention, and in otherembodiments white die 3900 and 3901 may each include a plurality of LEEs3901, as shown in FIGS. 40E and 40F. Furthermore, any or all of thetechniques and approaches described herein for white dies 210 withsubstrate 1710 may be applied to white dies without all or a portion ofsubstrate 1710.

In some embodiments the white die wafer may be singulated in a batch orsemi-batch mode. In one embodiment white dies are singulated using arotary cutter, for example a circular blade similar to that of apizza-cutting tool. In one embodiment multiple blades may be gangedtogether on a common shaft to make multiple cuts simultaneously,reducing singulation time. In some embodiments a custom one-piece bladehaving multiple cutting surfaces may be utilized. Such parallelism maybe used for other approaches, for example dicing or sawing or lasercutting or water jet cutting. Die cutting, in which a die ismanufactured that singulates all or a group of white die simultaneouslyis another batch singulation technique that may be utilized inembodiments of the present invention.

In some embodiments the blade used for singulation may be angled to forma sloped sidewall of the white die. In some embodiments a shaped blademay be used to impart a shape to the white die, as shown in FIGS. 41Aand 41B, where blade 4100 is shown to have two exemplary shapes,resulting in complementary shapes in phosphor 230.

In some embodiments the phosphor may be shaped to provide a surface or aportion of a surface to facilitate a transfer operation, for example apick-and-place operation. For example, a structure with a curvedphosphor surface may have a flat portion to facilitate pick-up using avacuum tool. In some embodiments one or more features may be formed inthe phosphor to act as identifying marks or fiducial marks that may berecognized by semi-automated or automated equipment. For example, insome embodiments such alignment of fiducial marks may be used by anautomated pick-and-place tool to identify and orient the white dies forpick-up as well as for placement on a wiring board. Such orientation mayinclude locating the center of the white die, the position of thecontacts, or the polarity of the white die (i.e., which contact is thep-contact and which is the n-contact). FIGS. 42A-42D depict someexamples of such fiducial marks, including chamfers (FIG. 42A), grooves(FIG. 42B), raised regions (FIG. 42C), and sloped surfaces (FIG. 42D).These examples are meant to demonstrate the concept but not be limitingto the invention. Such features may be designed to be visible by camerasor vision systems, or to reflect light differently from the rest of thesurface of white die 210 and thus facilitate identification of the whitedie as well as its orientation and position. Such alignment of fiducialfeatures may be formed as part of the white die formation process. Forexample, such features may be part of the mold, or they may be formedafter curing or partial curing of phosphor 230, e.g., by laser cutting,indentation, ablation or the like. The method of formation of thefiducial marks is not a limitation of the present invention.

In one embodiment of the present invention a reflecting layer is formedon all or a portion of the bottom surface of white die 210 to reflectlight back in a direction away from the contacts. FIG. 43 shows a whitedie 4300 that includes reflecting layer 4310. Reflecting layer 4310 maybe reflective to a wavelength of light emitted by phosphor 230 and/orLEE 210. In some embodiments reflecting layer 4310 has a reflectivitygreater than 25% to a wavelength of light emitted by phosphor 230 and/orLEE 210. In some embodiments reflecting layer 4310 has a reflectivitygreater than 50% to a wavelength of light emitted by phosphor 230 and/orLEE 210. In some embodiments reflecting layer 4310 has a reflectivitygreater than 75% to a wavelength of light emitted by phosphor 230 and/orLEE 210.

There are a number of ways in which a reflecting layer may be formed. Inone embodiment a powder of a material that is reflective to a wavelengthof light emitted by phosphor 230 and/or LEE 210 is dispersed over moldsubstrate 410 after formation of LEE 210 on mold substrate 410, as shownin FIG. 44. As seen in FIG. 44, this may result in a portion 4410 of thepowder on top of LEE 210 and a portion 4420 of the powder directly onmold substrate 410. In some embodiments powder 4420 may adhere to moldsubstrate 410 but not adhere well to the top of LEE 210, and thestructure shown in FIG. 44 may be tilted, inverted, exposed to a jet ofgas, shaken or otherwise processed to remove powder 4410 on top of LEEs210. The white die formation process may then be applied to thestructure shown in FIG. 44, resulting in white die 4300 (FIG. 43) wherereflecting layer 4310 is composed of the reflecting powder. In someembodiments the reflective powder may include at least one of fumedsilica, fumed alumina, TiO₂ or the like; however, the composition of thereflective powder is not a limitation of the present invention. In someembodiments powder 4410 is formed of particles that have a dimension inthe range of about 1 μm to about 50 μm; however, the size of the powderparticles is not a limitation of the present invention. In someembodiments the layer of phosphor into which is adhered, embedded orinfused powder 4410 has a thickness in the range of about 0.1 μm toabout 30 μm; however, the thickness of this layer is not a limitation ofthe present invention.

Another aspect of this approach is that it may be used to modify theadhesion of cured phosphor 230 to mold substrate 410, similar to whathas been described elsewhere herein. For example, if the reflectivelayer is formed from a powder, the powder may also reduce the adhesionof cured phosphor 230 to mold substrate 410. If the reflective layer isa film, as discussed subsequently, it may act to or be engineered toreduce the adhesion of cured phosphor 230 to mold substrate 410, similarto the discussion related to the mold release film.

In another embodiment of this approach, the reflecting layer is formedusing a reflective film. For example, a reflecting film 4510, similar toa mold release film, may be positioned over a portion of mold substrate410, as shown in FIG. 45A. After formation and curing of phosphor 230(FIG. 45B) and singulation (FIG. 45C), reflecting film 4510 adheres toand/or is embedded into cured phosphor 230 of the white die instead ofacting to reduce adhesion between cured phosphor 230 and mold substrate410, as is the case with the mold release film. As discussed herein, thefilm may by itself or in combination with other approaches be used tocontrol die and contact relief. In some embodiments reflective film 4510includes metal films or foils such as Cr, Al, Au, Ag, Cu, Ti, or thelike. In some embodiments reflective film 4510 may have a thickness inthe range of about 0.25 μm to about 50 μm; however, the thickness ofreflective film 4510 is not a limitation of the present invention. Insome embodiments reflective film 4510 is not thick enough to occludelight emitted from the side(s) of LEE 210. In one embodiment reflectivefilm 4510 is a foil that has been patterned with holes corresponding tothe position of LEEs 210 on mold substrate 410.

In one embodiment reflective layer 4310 may be deposited on moldsubstrate 410 and patterned to permit positioning of LEEs 210 directlyon mold substrate 410. In one embodiment reflective layer 4310 may beapplied selectively to mold substrate 410, for example through a shadowmask or selectively applied by evaporation, sputtering, spraying, or thelike. In one embodiment a reflecting layer may be formed by printing,for example screen, stencil, ink jet, gravure, flexo printing or thelike. In one embodiment reflective layer 4310 may be composed of morethan one layer of materials, for example a carrier and a reflectivelayer. In another embodiment reflective layer 4310 may be applied to thewhite wafer after it is formed. For example reflective layer 4310 couldbe formed by selective deposition of a reflecting layer on the bottom ofthe white wafer, where the reflective material is formed such that itdoes not come in electrical contact with any portion of the electricalcontacts of LEEs 210. In some embodiments this may be done by depositionof a metal layer, for example, Cr, Al, Au, Ag, Cu, Ti or the like, forexample by evaporation, physical vapor deposition, sputtering, chemicalvapor deposition, plating or the like. In some embodiments it may beaccomplished by lamination of a patterned foil.

In some embodiments, reflective layer 4310 may be insulating orrelatively insulating. For example, reflective layer 4310 may include adielectric minor or Bragg reflector, composed of alternating layers ofmaterials with different indices of refraction. Examples of suchmaterials include silicon dioxide, silicon nitride, or mixtures of thesematerials.

Reflective layer 4310 may be a specular or diffuse reflector. Forexample a reflective layer 4310 made from powder may provide a morediffuse reflector while a reflective layer 4310 made from a metal foilor film may provide a more specular reflector. Reflective layer 4310 mayalso include or consist essentially of a diffuse reflective film, suchas a white film, for example white PET, other white plastic films,White97 manufactured by WhiteOptics LLC, or MCPET manufactured byFurukawa. In some embodiments a white ink or paint may be appliedselectively to the back of the white wafer to form reflective layer4310. While application of materials has been discussed for applicationto the white wafer, such materials may be applied to the back ofsingulated white dies.

In some embodiments the molding of the phosphor to the die may becombined with one or more other processes. For example, in oneembodiment an optical element (e.g., a lens) may be co-molded or moldedsimultaneously to the white die. Such structures are shown in FIGS.46A-46C. FIG. 46A shows an example of a white die incorporating opticalelement 4610, while FIGS. 46B and 46C show examples of white dies withan optical element 4610 in which the substrates of the light-emittingelements have been partially or completely removed.

In one embodiment structures like those shown in FIGS. 46A-46C may beformed by adding an array of optical elements to the mold top 1031during the process for white die fabrication. FIG. 47A shows an opticalarray 4710 of optical elements between mold top 1031 and phosphor 230.FIG. 47B shows white dies on mold substrate 410 incorporating opticalelements 4610 after curing of the phosphor 230 and singulation. In someembodiments, optical element 4610 may be a Fresnel lens or aconventional lens. In some embodiments optical element 4610 mayinitially be part of an array of optical elements such as optical array4710 as discussed above, while in other embodiments one or more opticalelements 4610 may be positioned individually in the formation process.In one embodiment optical array 4710 may be all or a portion of the moldtop 1031.

In another embodiment optical array 4710 may be joined to a white diewafer 4810 after fabrication of white die wafer 4810, as shown in FIG.48. In one embodiment phosphor 230 of white die wafer 4810 may bepartially cured, mated to optical array 4710, and then be subjected toadditional curing to physically attach optical array 4710 to white diewafer 4810. In one embodiment an adhesive may be used to attach opticalarray 4710 to white die wafer 4810. Examples of adhesives includeoptical adhesives, spray adhesives, adhesive tape, polyurethane, thesame material used as the binder for phosphor 230, or the like. Themethod of attachment of optical array 4710 to white die wafer 4810 isnot a limitation of the present invention. In some embodiments theadhesive has an index of refraction that provides index matching betweenphosphor 230 and optical array 4710. In some embodiments, afterattachment of optical array 4710 to white die wafer 4810, singulationtakes place to separate the structure into smaller elements, eachcontaining at least one LEE 210 and one optical element 4610.

As shown, optical array 4710 includes or consists essentially of one ormore optical elements 4610, which in FIGS. 47A and 50 are aligned orsubstantially aligned with white dies 200. Optical array 4710 typicallyfeatures an array of optical elements 4610; in some embodiments, oneoptical element 4610 is associated with each white die 200, while inother embodiments multiple white dies 200 are associated with oneoptical element 4610, or multiple optical elements 4610 are associatedwith a single white die 200, or no engineered optical element isassociated with any white die 200, for example all or portions ofoptical array 4710 may be a plate with a flat or roughened surface. Inone embodiment, optical array 4710 includes elements or features toscatter, diffuse and/or spread out light generated by white dies 200.

Optical array 4710 may be substantially optically transparent ortranslucent. For example, optical array 4710 may exhibit a transmittancegreater than 80% for optical wavelengths ranging between approximately400 nm and approximately 600 nm. In one embodiment, optical array 4710includes or consists essentially of a material that is transparent to awavelength of light emitted by white dies 200. Optical array 4710 may besubstantially flexible or rigid. In some embodiments, optical array 4710includes multiple materials and/or layers. Optical elements 4610 may beformed in or on optical array 4710. Optical array 4710 may include orconsist essentially of, for example, acrylic, polycarbonate,polyethylene naphthalate (PEN), polyethylene terephthalate (PET),polycarbonate, polyethersulfone, polyester, polyimide, polyethylene,silicone, glass, or the like. Optical elements 4610 may be formed byetching, polishing, grinding, machining, molding, embossing, extruding,casting, or the like. The method of formation of optical elements 4610is not a limitation of embodiments of the present invention.

Optical elements 4610 associated with optical array 4710 may all be thesame or may be different from each other. Optical elements 4610 mayinclude or consist essentially of, e.g., a refractive optic, adiffractive optic, a total internal reflection (TIR) optic, a Fresneloptic, or the like, or combinations of different types of opticalelements. Optical elements 4610 may be shaped or engineered to achieve aspecific light distribution pattern from the array of light emitters,phosphors and optical elements.

As used herein, “alignment” and “aligned” may mean that the center ofone structure, for example a white die 200, is aligned with the centerof another structure, for example an optical element 4610; however, thisis not a limitation of the present invention, and in other embodiments,alignment refers to a specified relationship between the geometry ofmultiple structures.

While the discussion above has mainly focused on light-emitting devicesthat include a phosphor, this approach may be used as an approach toeconomically make light-emitting devices without the phosphor, where thematerial surrounding the LEE is a transparent material 4910 with nolight-conversion material, as shown in FIGS. 49A-49E. This may be calleda “clear die” 4900. In this case the transparent material may be calleda binder or an encapsulant. In this case the structure would appearsimilar to the examples discussed above, with the difference being thatthere is no light-conversion material present and the light emitted bysuch device is that emitted by the LEE. In some embodiments othermaterials may be present in the binder, for example material to scatterthe light. FIGS. 49A-49E show examples of clear dies 4900 that includeLEEs 210 and binder or encapsulant 4910. Any or all of the variationsdiscussed with respect to this invention may be used to produce cleardies. This approach permits the low-cost manufacture of clear dies invery large volumes. In some embodiments LEE 210 may include or consistessentially of an LED. In some embodiments LEE 210 may emit light in anyvisible color range, for example, red, orange, yellow, green, amber,blue, etc., or in wavelengths outside of the visible range, e.g.,infrared and ultraviolet. FIGS. 49A-49C show examples of clear dies 4900with various shapes of binder 4910, while FIG. 49D shows an example of aclear die with a co-molded optical fiber 4920. Optical fiber 4920 may beused for example, for out-coupling of light or monitoring of LEE 210optical characteristics. Such optical fiber coupling may also be usedwith white dies. FIG. 49E shows clear die 4900 integrated with anoptical element 4610, as discussed above with respect to white dies.

FIGS. 50-58 present different embodiments of the present invention thatfeature one or more optical elements. FIG. 50 shows the structure ofFIGS. 27 and 28 with integrated optical elements. In FIG. 50, each whitedie 200 has associated therewith an optical element 4610.

As shown, an optic 5010 includes or consists essentially of one or moreoptical elements 4610, which in FIG. 50 are aligned or substantiallyaligned with white dies 200. Optic 5010 typically features an array ofoptical elements 4610; in some embodiments, one optical element 4610 isassociated with each white die 200, while in other embodiments multiplewhite dies 200 are associated with one optical element 4610, or multipleoptical elements 4610 are associated with a single white die 200, or noengineered optical element is associated with any white die 200, forexample optic 5010 may be a plate with a flat or roughened surface. Inone embodiment, optic 5010 includes elements or features to scatter,diffuse and/or spread out light generated by white dies 200.

Optic 5010 may be substantially optically transparent or translucent.For example, optic 5010 may exhibit a transmittance greater than 80% foroptical wavelengths ranging between approximately 400 nm andapproximately 600 nm. In one embodiment, optic 5010 includes or consistsessentially of a material that is transparent to a wavelength of lightemitted by white dies 200. Optic 5010 may be substantially flexible orrigid. In some embodiments, optic 5010 is composed of multiple materialsand/or layers. Optical elements 4610 may be formed in or on optic 5010.Optic 5010 may include or consist essentially of, for example, acrylic,polycarbonate, polyethylene naphthalate (PEN), polyethyleneterephthalate (PET), polycarbonate, polyethersulfone, polyester,polyimide, polyethylene, silicone, glass or the like. Optical elements4610 may be formed by etching, polishing, grinding, machining, molding,embossing, extruding, casting, or the like. The method of formation ofoptical elements 4610 is not a limitation of embodiments of the presentinvention.

Optical elements 4610 associated with optic 5010 may all be the same ormay be different from each other. Optical elements 4610 may include orconsist essentially of, e.g., a refractive optic, a diffractive optic, atotal internal reflection (TIR) optic, a Fresnel optic, or the like, orcombinations of different types of optical elements. Optical elements4610 may be shaped or engineered to achieve a specific lightdistribution pattern from the array of light emitters, phosphors andoptical elements.

The space 5020 between the back side of optic 5010 and white die 200,shown in FIG. 50, may be a partial vacuum or be filled with air, filledwith a fluid or other gas or filled or partially filled with one or moreother materials. In one embodiment, region 5020 is filled or partiallyfilled with a transparent material, similar or identical to the materialthat is used as the binder for phosphor 230, to reduce TIR losses inwhite dies 200 and to provide enhanced optical coupling between whitedies 200 and optics 4610.

The structure shown in FIG. 51 is similar to that shown in FIG. 50;however, in FIG. 51, depressions 5100 are formed in optic 5010, toaccommodate or partially accommodate white dies 200. White dies 200 maybe formed or inserted into depressions 5100, for example in a batchprocess or using a pick-and-place tool. White dies 200 may be held indepressions 5100 mechanically, or with an adhesive or glue. In oneembodiment, white dies 200 are held in place by a transparent materialsimilar or identical to the binder or matrix used with phosphor 230. Inone embodiment, depression 5100 is larger than white die 200. In oneembodiment, depression 5100 is sized to just accommodate white die 200.FIGS. 52 and 53 show components of the structure of FIG. 51 at an earlystage of manufacture. FIG. 52 shows optic 5010 with depressions 5100.FIG. 53 shows LEE substrate 2720, conductive traces 2730 and white dies200. These two structures shown in FIGS. 52 and 53 are mated together toform the structure in FIG. 51.

The structure shown in FIG. 54 is similar to that shown in FIG. 51;however, in the case of the structure of FIG. 54, white dies 200 areformed or placed into depressions 5100 in optic 5010 with the contactsfacing out, and conductive traces 2730 are formed over optic 5010 andcontacts 220, electrically coupling white dies 200. In this embodiment,LEE substrate 2720 is eliminated. Conductive traces 2730 may be formedusing a variety of methods, for example physical vapor deposition,evaporation, sputtering, chemical vapor deposition, lamination,lamination and patterning, plating, printing, ink jet printing, screenprinting, gravure printing, flexo printing or the like. In oneembodiment, a reflective surface 5410 is formed over the back of optic5010 so that all or a substantial or controlled portion of light emittedfrom the back side of white dies 200 is reflected back toward optics4610. The reflective surface 5410 may include a metal such as gold,silver, aluminum, copper or the like and may be deposited byevaporation, sputtering, chemical vapor deposition, plating,electroplating or the like, or may include a reflective coating such aspaint, ink or the like, for example white ink or white paint. If thereflective coating is electrically conductive, it may be isolated fromconductive traces 2730 or may be isolated from (e.g., removed in) theregions occupied by conductive traces 2730. The reflective coating maybe non-conductive. The reflective coating may be formed either over orunder conductive traces 2730. The reflective coating may cover all orportions of white dies 200 and/or conductive traces 2730. The reflectivecoating may also include other materials, e.g., a Bragg reflector, orone or more layers of a specular or diffuse reflective material. In oneembodiment, optic 5010 is backed with a reflective material, e.g.,White97 manufactured by WhiteOptics LLC or MCPET manufactured byFurukawa, or any other reflective material. In one embodiment,conductive traces 2730 include or are formed of a material reflective toa wavelength of light emitted by white dies 200 and are patterned toprovide a region of reflective material surrounding white dies 200. Theuse of such reflective materials, or a reflective LEE substrate 2720,may be applied to any configuration of light system, for example thoseshown in FIGS. 50-57. FIG. 55 shows the structure of FIG. 54 at an earlystage of manufacture, prior to formation of conductive traces 2730 andoptional reflective layer 5410.

The structures shown in FIGS. 56 and 57 are similar to that shown inFIG. 54; however, in this case conductive traces 2730 are formed overoptic 5010 before formation or placement of white dies 200, as shown inFIG. 56. After formation or placement of white dies 200 in depressions5100, contacts 220 on white dies 200 are electrically coupled toconductive traces 2730 using jumpers (i.e., discrete conductors) 5710.Jumpers 5710 may be formed by a variety of different techniques. In oneembodiment, conductive material is formed and patterned over the surfaceof optic 5010, for example by evaporation, sputtering, lamination,plating, or the like, and patterning may be performed usingphotolithography, shadow mask, stencil mask, or the like. In oneembodiment, jumpers 5710 are formed by printing, for example by screenprinting, stencil printing, ink jet printing, or the like. In oneembodiment jumpers 5710 are formed by wire bonding. Jumpers 5710 mayhave a rectangular shape, but this is not a limitation of the presentinvention and in other embodiments jumpers 5710 have trapezoidal, squareor any arbitrary shape. Jumpers 5710 may include one or more conductivematerials, for example aluminum, gold, silver, platinum, copper, carbon,conductive oxides or the like. Jumper 5710 may have a thickness in therange of about 50 nm to about 100 μm. In one embodiment, jumper 5710 hasa thickness in the range of about 5 μm to about 30 μm. In oneembodiment, jumpers 5710 include materials used for conductive traces2730 and/or are formed using methods used for forming conductive traces2730. The method of formation and composition of jumper 5710 are notlimitations of the present invention.

The examples discussed above for white die 200 show one LEE 210 in eachwhite die 200. However, this is not a limitation of the presentinvention and in other embodiments each white die 200 includes aplurality of LEE 210.

The examples discussed above for white dies 200 show white dies 200 asbeing square and having sidewalls perpendicular to the contact face ofLEE 210. However, this is not a limitation of the present invention andin other embodiments white die 200 is rectangular, hexagonal, circular,triangular, or has any arbitrary shape, and/or has sidewalls forming anyangle with respect to the surface of LEE 210 including contacts 220.While the term white die, for example related to white die 200, has beenused to describe a structure producing white light, this is not alimitation of the present invention, and in other embodiments, differentcolor LEEs 210 and different phosphors (one or more) may be used toproduce other colors, for example amber, green or any arbitrary color orspectral power distribution. In other embodiments, a white die 200includes a plurality of LEEs 210. In some embodiments, the LEEs 210 areall the same, while in other embodiments the LEEs 210 include two ormore groups of different LEEs 210, for example emitting at differentwavelengths. In some embodiments LEE 210 may include or consistessentially of an organic light emitter.

While the discussion above has mainly focused on light-emitting devices,embodiments of the present invention may also be used for devices thatabsorb light, for example detectors or photovoltaic devices. FIG. 58Ashows an exemplary device 5800 that includes a light-absorbing element(LAE) 5810 and binder 5820. In one embodiment LAE 5810 is configuredwith a flip-chip geometry, in which contacts 220 are positioned on aface opposite a detecting face 5830. In one embodiment LAE 5810 has astructure similar to that for LEE 1700 shown in FIG. 17A. In oneembodiment the substrate for LAE 5810 is partially or completelyremoved. LAE 5810 may be configured to detect one or more wavelengthsover a wide range of wavelength ranges, both within and outside thevisible light spectrum. In various embodiments LAE 5810 may beconfigured to detect UV light, IR light, x-rays, visible light or anyportion of the electromagnetic spectrum for which a detector isavailable. In some embodiments LAE 5810 may include GaAs, InAs, AlAs,GaN, InN, AN, GaP, InP, AlP, InGaP, InAlP, InGaAlP, ZnO, II—VI materialsor the like or various combinations of two or more of these materials.The material from which LAE 5810 is composed is not a limitation of thepresent invention.

In some embodiments LAE 5810 may be a Schottky detector, a p-n junctiondetector, a photoelectric detector, a photocell, a photoresistor, aphotodiode, a phototransistor, a charge-coupled device, a CMOS imager orthe like. The type of LAE 5810 and method by which LAE 5810 operates arenot limitations of the present invention.

In one embodiment binder 5820 is transparent to a wavelength of light tobe detected by LAE 5810. In one embodiment binder 5820 may be partiallyabsorbing and the absorption band of binder 5820 may be used to selectone or more wavelength ranges to be detected by LAE 5810 from the rangeof incident wavelength ranges. For example binder 5820 may effectivelyact as a low-pass filter, a high-pass filter, a bandpass filter orvarious combinations of these.

In some embodiments binder 5820 may further include other materials toenhance one or more aspects of the performance of device 5800. Forexample in one embodiment binder 5820 may include materials to absorbone or more wavelengths of light, to act as a filter. In one embodimentbinder 5820 includes a wavelength-conversion material, similar to thatdescribed above. In one embodiment this may be used to shift an incidentwavelength to a different wavelength to be detected by LAE 5810. Forexample a phosphor may be added to binder 5820 to shift one or morewavelengths of incident light (e.g., blue light) to one or moredifferent wavelengths (e.g., yellow light) that impinge on LAE 5810. Inthis way one or a small number of LAEs 5810 may be used in combinationwith a number of wavelength-conversion materials to produce a family ofdetectors spanning a wide wavelength range, without the need to have arelatively large number of different LAEs 5810.

As discussed herein with respect to white dies, binder 5820 may beshaped. In some embodiments binder 5820 is shaped to increase thecollection of light by LAE 5810. FIG. 58B shows an example of device5800 having shaped binder 5820 having a dome-like shape. In someembodiments shaped binder 5820 is combined with one or more additives tobinder 5820, for example a wavelength-conversion material.

In some embodiments device 5800 may include more than one LAE 5810. Inone embodiment device 5800 includes three LAEs 5810, identified as LAEs5810, 5810′, and 5810″ in FIG. 58C. In one embodiment LAE 5810 detectsred wavelengths, LAE 5810′ detects green wavelengths, and LAE 5810″detects blue wavelengths, and the combination may be used as a colorsensor by evaluating the relative output signals from the threedifferent LAEs.

In some embodiments LAE 5810 is a photovoltaic device or solar cell, andis designed to produce power from incident radiation (typically, but notnecessarily, in the visible range). Such a photovoltaic device may bemade of a wide variety of materials. In some embodiments LAE 5810 mayinclude GaAs, InAs, AlAs, GaN, InN, AN, GaP, InP, AlP, InGaP, InAlP,InGaAlP, ZnO, II—VI materials or the like or various combinations of twoor more of these materials. The material from which LAE 5810 is made isnot a limitation of the present invention. In some embodiments LAE 5810is a single-junction solar cell, while in other embodiments LAE 5810 isa multi-junction solar cell. As discussed herein with respect tolight-emitting elements and detectors, photovoltaic devices producedusing embodiments of the present invention may include in variousembodiments a transparent binder, additives to the binder,wavelength-conversion materials, shaped binder, optics, multiple LAEs5810 per device, and the like.

In some embodiments a photovoltaic device made using this invention mayadditionally include one or more optics to increase collection or to actas concentrators, for example as shown in FIG. 59A. FIG. 59A shows adevice 5900 that includes a solar cell 5910, a binder 5820, and an optic4610. In one embodiment the optical function for collection orconcentration is carried out using a shaped binder 5820, as shown inFIG. 59B for device 5901.

In some embodiments binder 5820 may further include other materials toenhance one or more aspects of the performance of devices 5900, 5901.For example in one embodiment binder 5820 may include materials toabsorb one or more wavelengths of light, to act as a filter. In oneembodiment binder 5820 includes a wavelength-conversion material,similar to that described above with respect to white dies. In oneembodiment this may be used to shift an incident wavelength to adifferent wavelength to be absorbed by solar cell 5910. For example aphosphor may be added to binder 5820 to shift one or more wavelengths ofincident light to one or more different wavelengths of light thatimpinge on solar cell 5910. In this way a larger portion of the solarspectrum may be usefully absorbed by solar cell 5910. In someembodiments this may permit the use of a lower cost solar cell 5910, forexample one with fewer junctions. In one embodiment more than onedifferent solar cell, each absorbing light in a different wavelengthrange, may be incorporated into one packaged device, similar to thestructure shown in FIG. 58C.

Embodiments of the present invention may be applied to devices thatneither emit nor detect light, identified as electronic-only devices,where the purpose of application of this invention is in someembodiments reduction in cost. In various embodiments, a relativelylarge number of electronic devices, specifically chips or discretedevices or integrated circuits may be packaged in a polymer-basedmaterial (like the binder detailed above) using a high-volume, low-cost,base process. In some embodiments of this approach, binder 5820 need notbe transparent but may be translucent or opaque. As discussed hereinwith respect to light-emitting elements, detectors, and photovoltaicdevices, electronic-only devices produced in accordance with embodimentsof the present invention may include additives to the binder, shapedbinder, multiple devices, and the like.

In one embodiment an electronic-only device of the present invention isa packaged electronic only device, such as that shown in FIG. 60A, inwhich device 6000 includes electronic-only device 6010 and binder 6020.In some embodiments electronic only device 6010 may have a larger numberof contacts than would a light emitter or a detector. For exampleelectronic-only device 6010 may include more than ten contacts or morethan 100 contacts or even larger number of contacts.

FIG. 60B shows another example, device 6001, incorporating a heatspreader 6030. A heat spreader, as utilized herein, is a volume ofmaterial with a relatively high thermal conductivity, in particularhigher than that of binder 6020, which may be used to transfer heat fromelectronic-only device 6010 to ambient or to an additionalthermal-management system. In some embodiments heat spreader 6030 is ametal, for example Al, Cu, Au, Ag, Cr, or the like. In some embodimentsheat spreader 6030 is a ceramic, for example AlN, SiC, polycrystallineSiC, polycrystalline AlN, or the like. In some embodiments heat spreader6030 is a monolithic component, but this is not a limitation of thepresent invention, and in other embodiments heat spreader 6030 maycomprise multiple discrete and separate portions, as shown in FIGS. 60Cand 60D respectively. While heat spreader 6030 is shown as a square orrectangle in FIGS. 60C and 60D, this is not a limitation of the presentinvention, and in other embodiments heat spreader 6030 may have anyshape or size. In one embodiment heat spreader 6030 is a heat pipe.

In another embodiment a connector may be added to a device, for examplean electronic-only device. In one embodiment a connector 6040 is addedon top of electronic-only device 6010 and held in place at least in partby the presence of binder 6020, as shown in FIG. 60E.

In another embodiment one or more devices may be stacked on top of eachother, as shown in FIG. 61. FIG. 61 shows electronic-only device 6010′formed over electronic-only device 6010. FIG. 61 also shows optionalvias through electronic-only device 6010, permitting electrical couplingbetween electronic-only devices 6010′ and 6010. Other methods may beused to electrically couple devices, for example wire bonding, solder,conductive adhesives, etc. While FIG. 61 shows electronic-only device6010 and 6010′ having different sizes, that is not a limitation of thepresent invention and in other embodiments electronic-only device 6010and electronic-only device 6010′ may have the same or substantially thesame size.

In another embodiment electronic-only and other (for examplelight-detecting and/or light-emitting) devices may be packaged in thesame binder, as shown in FIG. 62. FIG. 62 shows electronic-only device6010 adjacent to light-detection device 5810. This approach may be usedto provide some additional capability, for example signal conditioning,communications, memory or the like. In one embodiment electronic-onlydevice 6010 and light-detection device 5810 communicate through each oftheir respective contacts by way of connections on the circuit board towhich they are ultimately mounted. In one embodiment internal connectionis used, for example similar to the vias shown in FIG. 61 or wire bonds,etc.

While the discussion herein mainly focuses on down-conversion, that isthe use of a wavelength-conversion material or phosphor to shift a shortwavelength to a longer wavelength, that is not a limitation of thepresent invention and in other embodiments up-conversion or acombination of up-conversion and down-conversion may be used.

Other embodiments of this invention may have additional or fewer stepsor components or may be modified or carried out in a different order. Ingeneral in the above discussion the arrays of light emitters, wells,optics and the like have been shown as square or rectangular arrays;however, this is not a limitation of the present invention and in otherembodiments these elements are formed in other types of arrays, forexample hexagonal, triangular or any arbitrary array. In someembodiments, these elements are grouped into different types of arrayson a single substrate.

The terms and expressions employed herein are used as terms andexpressions of description and not of limitation, and there is nointention, in the use of such terms and expressions, of excluding anyequivalents of the features shown and described or portions thereof. Inaddition, having described certain embodiments of the invention, it willbe apparent to those of ordinary skill in the art that other embodimentsincorporating the concepts disclosed herein may be used withoutdeparting from the spirit and scope of the invention. Accordingly, thedescribed embodiments are to be considered in all respects as onlyillustrative and not restrictive.

What is claimed is:
 1. An electronic device comprising: a solid shapedvolume of a polymeric binder; suspended within the polymeric binder, asemiconductor die having a first face, a second face opposite the firstface, and at least one sidewall spanning the first and second faces, thesemiconductor die being a bare-die light-detecting element comprising aplurality of active semiconductor layers configured to cooperativelyabsorb light over a detected wavelength range and produce electricalcharge therefrom; a reflecting layer disposed on a surface of thepolymeric binder or disposed within at least a portion of the polymericbinder proximate the semiconductor die; and disposed on the first faceof the semiconductor die, at least two spaced-apart contacts each (i)having a free terminal end not covered by the polymeric binder, (ii)being available for electrical connection, and (iii) contacting adifferent active semiconductor layer of the semiconductor die, wherein(i) at least a portion of the polymeric binder is transparent to awavelength of light within the detected wavelength range and (ii) thereflecting layer has a reflectivity of at least 50% to a wavelength oflight within the detected wavelength range.
 2. The electronic device ofclaim 1, wherein the polymeric binder contains therein awavelength-conversion material for absorption of at least a portion oflight incident on the electronic device and emission of converted lighthaving a different wavelength.
 3. The electronic device of claim 2,wherein substantially all of the light absorbed by the light-detectingelement is converted light.
 4. The electronic device of claim 2, whereinthe different wavelength of the converted light is within the detectedwavelength range.
 5. The electronic device of claim 2, wherein thewavelength-conversion material comprises at least one of a phosphor orquantum dots.
 6. The electronic device of claim 2, wherein the polymericbinder comprises a plurality of discrete regions, at least one of whichcomprises the polymeric binder without wavelength-conversion materialtherein.
 7. The electronic device of claim 2, wherein the reflectinglayer has a reflectivity of at least 50% to a wavelength of lightemitted by the wavelength-conversion material.
 8. The electronic deviceof claim 2, wherein the reflecting layer has a reflectivity of at least75% to a wavelength of light emitted by the wavelength-conversionmaterial.
 9. The electronic device of claim 1, wherein the reflectivityof the reflecting layer to a wavelength of light within the detectedwavelength range is at least 75%.
 10. The electronic device of claim 1,wherein the polymeric binder comprises therein an absorbing material forabsorption of at least a portion of the spectrum of light incident uponthe electronic device.
 11. The electronic device of claim 10, wherein awavelength of the portion of the spectrum of light absorbed by theabsorbing material is longer than the detected wavelength range.
 12. Theelectronic device of claim 10, wherein a wavelength of the portion ofthe spectrum of light absorbed by the absorbing material is shorter thanthe detected wavelength range.
 13. The electronic device of claim 10,wherein the polymeric binder comprises a plurality of discrete regions,at least one of which comprises the polymeric binder without theabsorbing material therein.
 14. The electronic device of claim 1,wherein the polymeric binder comprises therein a reflective material forreflection of at least a portion of the spectrum of light incident uponelectronic device.
 15. The electronic device of claim 14, wherein awavelength of the portion of the spectrum of light reflected by thereflective material is longer than the detected wavelength range. 16.The electronic device of claim 14, wherein a wavelength of the portionof the spectrum of light reflected by the reflective material is shorterthan the detected wavelength range.
 17. The electronic device of claim14, wherein the polymeric binder comprises a plurality of discreteregions, at least one of which comprises the polymeric binder withoutthe reflective material therein.
 18. The electronic device of claim 1,wherein at least portions of the contacts protrude from the polymericbinder.
 19. The electronic device of claim 1, wherein only a portion ofeach said sidewall protrudes from the polymeric binder, a portion ofeach said sidewall being covered with the polymeric binder.
 20. Theelectronic device of claim 1, wherein the polymeric binder comprises atleast one of silicone or epoxy.
 21. The electronic device of claim 1,wherein the semiconductor die comprises a bare-die photovoltaic cell.22. The electronic device of claim 1, wherein the semiconductor diecomprises at least one of a bare-die photovoltaic cell, a bare-dieinfrared detector, a bare-die ultraviolet detector, a bare-die visiblelight detector, or a bare-die x-ray detector.
 23. The electronic deviceof claim 1, wherein the semiconductor die comprises at least one of ap-n junction, a Schottky junction, a photoelectric detector, aphotocell, a photoresistor, a photodiode, a phototransistor, acharge-coupled device, or a bare-die imaging chip.
 24. The electronicdevice of claim 1, wherein the semiconductor die comprises asemiconductor material comprising at least one of GaAs, AlAs, InAs, GaP,AlP, InP, ZnO, CdSe, CdTe, ZnTe, GaN, AN, InN, silicon, or an alloy ormixture thereof.
 25. The electronic device of claim 1, wherein thepolymeric binder and the semiconductor die collectively define anapproximately rectangular solid having approximately 90° corners betweenadjacent faces thereof.
 26. The electronic device of claim 1, wherein atleast a portion of the reflecting layer is substantially parallel to thefirst face of the semiconductor die.
 27. The electronic device of claim1, wherein the reflecting layer is approximately parallel to andapproximately coplanar with the first face of the semiconductor die. 28.The electronic device of claim 1, wherein the polymeric binder has athickness between 5 μm and 4000 μm.
 29. The electronic device of claim1, further comprising an optical element positioned to couple light tothe semiconductor die.
 30. The electronic device of claim 1, wherein thereflecting layer comprises at least one of (i) a reflecting film or (ii)a plurality of particles.
 31. The electronic device of claim 1, whereinthe plurality of active semiconductor layers of the semiconductor dieare not disposed on a semiconductor substrate.
 32. The electronic deviceof claim 1, wherein the reflecting layer is a substantially diffusereflector.
 33. The electronic device of claim 1, wherein the reflectinglayer is a substantially specular reflector.
 34. The electronic deviceof claim 1, further comprising one or more additional semiconductor diessuspended within the polymeric binder.
 35. The electronic device ofclaim 1, wherein the polymeric binder coats the second face of thesemiconductor die, the at least one sidewall, and at least a portion ofthe first face of the semiconductor die.
 36. The electronic device ofclaim 1, further comprising one or more alignment marks on the surfaceof the polymeric binder for at least one of alignment or orientation ofthe semiconductor die.
 37. The electronic device of claim 1, wherein thefirst face of the semiconductor die comprises at least two non-coplanarportions each having at least one said contact thereon.
 38. Theelectronic device of claim 1, wherein at least a portion of a topsurface of the polymeric binder is curved.
 39. The electronic device ofclaim 10, wherein a wavelength of the portion of the spectrum of lightabsorbed by the absorbing material is within the detected wavelengthrange.
 40. The electronic device of claim 14, wherein a wavelength ofthe portion of the spectrum of light reflected by the reflectivematerial is within the detected wavelength range.
 41. The electronicdevice of claim 1, further comprising an optical element positioned tocouple light to the polymeric binder.